Efficient Preconstruction of Three‑Dimensional Graphene Networks for Thermally Conductive Polymer Composites

Electronic devices generate heat during operation and require efficient thermal management to extend the lifetime and prevent performance degradation.Featured by its exceptional thermal conductivity,graphene is an ideal functional filler for fabricating thermally conductive polymer composites to provide efficient thermal management.Extensive studies have been focusing on constructing graphene networks in polymer composites to achieve high thermal conductivities.Compared with conventional composite fabrications by directly mixing graphene with polymers,preconstruction of three-dimensional graphene networks followed by backfilling polymers represents a promising way to produce composites with higher performances,enabling high manufacturing flexibility and controllability.In this review,we first summarize the factors that affect thermal conductivity of graphene composites and strategies for fabricating highly thermally conductive graphene/polymer composites.Subsequently,we give the reasoning behind using preconstructed three-dimensional graphene networks for fabricating thermally conductive polymer composites and highlight their potential applications.Finally,our insight into the existing bottlenecks and opportunities is provided for developing preconstructed porous architectures of graphene and their thermally conductive composites.

Direct ink writing of multifunctional gratings with gel-like MXene/norepinephrine ink for dynamic electromagnetic interference shielding and patterned Joule heating

Intelligent electromagnetic interference(EMI)shielding modulators with a wide tuning range and cyclic stability are urgently needed but their fabrication remains challenging.A gel-like MXene/norepinephrine ink is developed and multifunctional MXene gratings with wide EMI shielding effectiveness(SE)tuning range,superior reversibility,and high mechanical flexibility are constructed by direct ink writing approach for dynamic EMI shielding and patterned Joule heating applications.The modulable MXene/norepinephrine grating with a high conductivity of 3510 S·cm-1 can conveniently realize the seamless modulation of the EMI SE by adjusting the angle between the MXene grating filaments and the electric field of the incident electromagnetic waves,offering highly reversible switching between shielding“On”(28.0 dB)and“Off”(0.5 dB)states.Notably,due to the optimized integration of the MXene ink and the rationally designed pattern,a superior specific EMI SE of 95,688.2 dB·cm^(2)·g^(-1) is achieved in the“On”state.Furthermore,the MXene/norepinephrine ink can be used to fabricate many complex patterned gratings with superior stability,instant responsibility,and superb mechanical flexibility,exhibiting a unique patterned Joule heating behavior.Direct writing of multifunctional gratings paves a means for developing intelligent EMI shielding materials,wearable electronic devices,and advanced thermal management materials.

3D Lamellar-Structured Graphene Aerogels for Thermal Interface Composites with High Through-Plane Thermal Conductivity and Fracture Toughness

Although thermally conductive graphene sheets are efficient in enhancing in-plane thermal conductivities of polymers,the resulting nanocomposites usually exhibit low through-plane thermal conductivities,limiting their application as thermal interface materials.Herein,lamellarstructured polyamic acid salt/graphene oxide(PAAS/GO)hybrid aerogels are constructed by bidirectional freezing of PAAS/GO suspension followed by lyophilization.Subsequently,PAAS monomers are polymerized to polyimide(PI),while GO is converted to thermally reduced graphene oxide(RGO)during thermal annealing at 300℃.Final graphitization at 2800℃ converts PI to graphitized carbon with the inductive effect of RGO,and simultaneously,RGO is thermally reduced and healed to high-quality graphene.Consequently,lamellar-structured graphene aerogels with superior through-plane thermal conduction capacity are fabricated for the first time,and its superior through-plane thermal conduction capacity results from its vertically aligned and closely stacked high-quality graphene lamellae.After vacuum-assisted impregnation with epoxy,the resultant epoxy composite with 2.30 vol% of graphene exhibits an outstanding through-plane thermal conductivity of as high as 20.0 W m^−1 K^−1,100 times of that of epoxy,with a record-high specific thermal conductivity enhancement of 4310%.Furthermore,the lamellar-structured graphene aerogel endows epoxy with a high fracture toughness,~1.71 times of that of epoxy.

Super-Tough and Environmentally Stable Aramid Nanofiber@MXene Coaxial Fibers with Outstanding Electromagnetic Interference Shielding Efficiency

Although electrically conductive and hydrophilic MXene sheets are promising for multifunctional fibers and electronic textiles,it is still a challenge to simultaneously enhance both conductivity and mechanical properties of MXene fibers because of the high rigidity of MXene sheets and insufficient inter-sheet interactions.Herein,we demonstrate a core-shell wet-spinning methodology for fabricating highly conductive,super-tough,ultra-strong,and environmentally stable Ti_(3)C_(2)T_(x) MXene-based core-shell fibers with conductive MXene cores and tough aramid nanofiber(ANF)shells.The highly orientated and low-defect structure endows the ANF@MXene core-shell fiber with supertoughness of~48.1 MJ m^(-3),high strength of~502.9 MPa,and high conductivity of~3.0×10^(5)S m^(-1).The super-tough and conductive ANF@MXene fibers can be woven into textiles,exhibiting an excellent electromagnetic interference(EMI)shielding efficiency of 83.4 dB at a small thickness of 213μm.Importantly,the protection of the ANF shells provides the fibers with satisfactory cyclic stability under dynamic stretching and bending,and excellent resistance to acid,alkali,seawater,cryogenic and high temperatures,and fire.The oxidation resistance of the fibers is demonstrated by their wellmaintained EMI shielding performances.The multifunctional core-shell fibers would be highly promising in the fields of EMI shielding textiles,wearable electronics and aerospace.

Direct Ink Writing of Highly Conductive MXene Frames for Tunable Electromagnetic Interference Shielding and Electromagnetic Wave-Induced Thermochromism

The highly integrated and miniaturized next-generation electronic products call for high-performance electromagnetic interference(EMI)shielding materials to assure the normal operation of their closely assembled components.However,the most current techniques are not adequate for the fabrication of shielding materials with programmable structure and controllable shielding efficiency.Herein,we demonstrate the direct ink writing of robust and highly conductive Ti3C2Tx MXene frames with customizable structures by using MXene/AlOOH inks for tunable EMI shielding and electromagnetic wave-induced thermochromism applications.The as-printed frames are reinforced by immersing in AlCl_(3)/HCl solution to remove the electrically insulating AlOOH nanoparticles,as well as cross-link the MXene sheets and fuse the filament interfaces with aluminum ions.After freeze-drying,the resultant robust and porous MXene frames exhibit tunable EMI shielding efficiencies in the range of 25-80 dB with the highest electrical conductivity of 5323 S m−1.Furthermore,an electromagnetic wave-induced thermochromic MXene pattern is assembled by coating and curing with thermochromic polydimethylsiloxane on a printed MXene pattern,and its color can be changed from blue to red under the high-intensity electromagnetic irradiation.This work demonstrates a direct ink printing of customizable EMI frames and patterns for tuning EMI shielding efficiency and visualizing electromagnetic waves.

Advancing green energy solution with the impetus of COVID-19 pandemic

The global energy system needs a revolutionary transition from today’s fossil fuel to a low carbon energy system by having deep carbonization in all energy demand sectors.Especially in the transport sector,fossil fuel-based vehicles contribute to a more massive amount of greenhouse gas emissions(GHG),mainly carbon dioxide(CO_(2))and particulate matter(PM2.5),affecting human health,society,and the climate system.Hydrogen and fuel cell technology is a promising low carbon transition pathway that supports GHG mitigation and achieves sustainable development.Although hydrogen and fuel cells are assuring,fuel cell vehicle expensiveness and the high cost of hydrogen production with the low carbon footprint are significant hindrances for its widespread deployment.Besides the situation above,the present corona virus(COVID-19)has devastated our global economy and ramps down the future of fossil fuel.It provides opportunities to rethink and reshape our energy system to a low carbon footprint.By utilizing the situation,governments and policymakers need to eliminate fossil fuel and invest in the hydrogen and fuel cell technologies deployment as future energy systems.This review article provides a technical overview of a low carbon energy system,production,and end-use service in a hydrogen economy perspective for developing a sustainable energy future.The techno-economic analysis of the different hydrogen production routines and fuel cell vehicles and their infrastructures are primarily focused.Finally,a long-term policy alignment was outlined to advance the hydrogen energy system for post-COVID-19 in the United Nation’s(UN)sustainable development goals framework.

Recent insights on iron based nanostructured electrocatalyst and current status of proton exchange membrane fuel cell for sustainable transport

Bridging the performance gap of the electrocatalyst between the rotating disk electrode(RDE) and membrane electrode assembly(MEA) level testing is the key to reducing the total cost of proton exchange membrane fuel cell(PEMFC) vehicles. Presently, platinum metal accounts for ~42% of the total cost of the PEMFC vehicles for usage in the cathode catalyst layer, where the sluggish oxygen reduction reaction(ORR) occurs. An alternative to the platinum catalyst, the Fe-N-C catalyst has attracted considerable interest for PEMFC due to its cost-effectiveness and high catalytic activity towards ORR. However, the excellent ORR activity of Fe-N-C obtained from RDE studies rarely translates the same performance into MEA operating conditions. Such a performance gap is mainly attributed to the lack of atomic-level understanding of Fe-N-C active sites and their ORR mechanism. Besides, unless the cost of expensive electrocatalyst is reduced, the total operation cost of the PEMFC vehicles remains constant. Therefore,developing highly efficient Fe-N-C catalysts from academic and industrial perspectives is critical for commercializing PEMFC vehicles. Here, the scope of the review is three-fold. First, we discussed the atomiclevel insights of Fe-N-C active sites and ORR mechanism, followed by unraveling the different iron-based nanostructured ORR electrocatalysts, including oxide, carbide, nitride, phosphide, sulfide, and singleatom catalysts. And then we bridged their ORR catalytic performance gap between the RDE and MEA tests for real operating conditions of PEMFC vehicles. Second, we focused on bridging the cost barriers of PEMFC vehicles between capital, operation, and end-user. Finally, we provided the path to achieve sustainable development goals by commercializing PEMFC vehicles for a better world.

Layered Birnessite Cathode with a Displacement/Intercalation Mechanism for High-Performance Aqueous Zinc-Ion Batteries

Mn-based rechargeable aqueous zinc-ion batteries(ZIBs)are highly promising because of their high operating voltages,attractive energy densities,and eco-friendliness.However,the electrochemical performances of Mn-based cathodes usually suffer from their serious structure transformation upon charge/discharge cycling.Herein,we report a layered sodium-ion/crystal water co-intercalated Birnessite cathode with the formula of Na0.55Mn2O4·0.57H2O(NMOH)for high-performance aqueous ZIBs.A displacement/intercalation electrochemical mechanism was confirmed in the Mn-based cathode for the first time.Na+and crystal water enlarge the interlayer distance to enhance the insertion of Zn^2+,and some sodium ions are replaced with Zn^2+ in the first cycle to further stabilize the layered structure for subsequent reversible Zn^2+/H^+ insertion/extraction,resulting in exceptional specific capacities and satisfactory structural stabilities.Additionally,a pseudo-capacitance derived from the surface-adsorbed Na^+ also contributes to the electrochemical performances.The NMOH cathode not only delivers high reversible capacities of 389.8 and 87.1 mA h g^−1 at current densities of 200 and 1500 mA g^−1,respectively,but also maintains a good long-cycling performance of 201.6 mA h g^−1 at a high current density of 500 mA g^−1 after 400 cycles,which makes the NMOH cathode competitive for practical applications.

Electrically conductive and highly compressible anisotropic MXene-wood sponges for multifunctional and integrated wearable devices

Although piezoresistive sensors have wide applications in human motion detection and wearable elec-tronics,it is still a challenge to produce multifunctional and integrated sensors with wide working ranges and linear sensing responses.Herein,electrically conductive,highly compressible,and structurally anisotropic MXene-wood(MW)sponges are fabricated by converting balsa wood blocks to compressible wood sponges with extremely low density and highly anisotropic porous structure,followed by deco-rating with conductive MXene sheets.The MW sponge is utilized to assemble a piezoresistive sensor with a large working range of 0-25 kPa,wide linear sensing ranges of 5%-50%and 0-180°,and excellent long-term reliability under a bending angle of 30°for 5000 cycles.Additionally,the sensor is suitable for monitoring practical human physiological signals including pulse beating,and finger and wrist bending.An all-MW sponge-based multifunctional and integrated sensing system is constructed by integrating the MW sponge piezoresistive sensor,the MW sponge-based solid-state supercapacitor,and the MW sponge electrophysiological electrodes.The sensing system can concurrently detect surface electromyogram and tactile pressures,and hence realize real-time closed-loop controls.The multifunctional and integrated MW sponge sensing system would have great potentials in real-time pressure recognition and human-machine interfaces.

Rational Design of Biomolecules/Polymer Hybrids by Reversible Deactivation Radical Polymerization (RDRP) for Biomedical Applications

Hybrids,produced by hybridization of proteins,peptides,DNA,and other new biomolecules with polymers,often have unique functional properties.These properties,such as biocompatibility,stability and specificity,lead to various smart biomaterials.This review mainly introduces biomolecule polymer hybrid materials by reversible deactivation radical polymerization(RDRP),emphasizing reverse addition-fragmentation chain transfer(RAFT)polymerization,and nitroxide mediated polymerization(NMP).It includes the methods of RDRP to improve the biocompatibility of biomedical materials and organisms by surface modification.The key to the current synthesis of biomolecule polymer hybrids is to control polymerization.Besides,this review describes several different kinds of biomolecule polymer hybrid materials and their applications in the biomedical field.These progresses provide ideas for the investigation of biodegradable and highly bioactive biomedical soft tissue materials.The research hotspots of nanotechnology in biomedical fields are controlled drug release materials and gene therapy carrier materials.Research showed that RDRP method could improve the therapeutic effect and reduce the dosage and side effects of the drug.Specifically,by means of RDRP,the original materials can be modified to develop intelligent polymer materials as membrane materials with selective permeability and surface modification.

Multifunctional Waterborne Polyurethane Nanocomposite Films with Remarkable Electromagnetic Interference Shielding,Electrothermal and Solarthermal Performances

To impart polymers with high electrical conductivity and satisfactory electromagnetic interference shielding efficiency,it is crucial to efficiently construct interconnecting networks of conductive nanofillers in polymer matrices.Herein,on the basis of the three-dimensional(3D)skeleton and volume-exclusion effect of silane-modified tetra-needle ZnO(ST-ZnO)whiskers and the high conductivity of two-dimensional MXene nanosheets,multifunctional MXene/ST-ZnO/waterborne polyurethane(MTW)nanocomposite films are fabricated by coating of MXene on ST-ZnO followed by compounding with waterborne polyurethane.The 3D four-needles of the whiskers facilitate the formation of an interconnecting network in the waterborne polyurethane matrix,while the coating of MXene efficiently makes the interconnecting network of the whiskers conductive at a low amount of the MXene.The resultant MTW ternary nanocomposite film exhibits not only a high electrical conductivity of 4.8×10^(4)S/m,but also an excellent electromagnetic interference shielding effectiveness of over 70 dB in the X-band at a low thickness of 100µm.In addition,the ternary film also exhibits outstanding Joule heating performances with an equilibrium temperature of 113℃at a low driving voltage of 3 V.The multifunctional nanocomposite films are promising for applications in portable and wearable electronics and flexible electromagnetic interference shielding devices.

Electrically Conductive and Flame Retardant Graphene/Brominated Polystyrene/Maleic Anhydride Grafted High Density Polyethylene Nanocomposites with Satisfactory Mechanical Properties

Electrically conductive and flame-retardant maleic anhydride grafted high-density polyethylene(MA-HDPE) nanocomposites with satisfactory mechanical properties are fabricated by melt compounding MA-HDPE with polyethyleneimine(PEI)-modified reduced graphene oxide(PEI@RGO) as the conductive nanofiller and brominated polystyrene(BPS) as the flame retardant. The modification with PEI significantly improves the interfacial compatibility and dispersion of the RGO sheets in the MA-HDPE matrix, leading to electrically conductive nanocomposites with enhanced mechanical properties. Furthermore, the addition of 25 wt% of BPS makes the nanocomposite flame-retardant with a UL-94 V-0 rating. Thus, the multifunctional RGO/MA-HDPE nanocomposites with good electrical, flameretardant, and mechanical properties would have potential applications in construction and pipeline fields.

Fiber-reinforced Three-dimensional Graphene Aerogels for Electrically Conductive Epoxy Composites with Enhanced Mechanical Properties

To enhance the mechanical properties of three-dimensional graphene aerogels with aramid fibers,graphene/organic fiber aerogels are prepared by chemical reduction of graphene oxide in the presence of organic fibers of poly(p-phenylene terephthalamide)(PPTA) and followed by freeze-drying. Thermal annealing of the composite aerogels at 1300 ° C is adopted not only to restore the conductivity of the reduced graphene oxide component but also to convert the insulating PPTA organic fibers to conductive carbon fibers by the carbonization. The resultant graphene/carbon fiber aerogels(GCFAs) exhibit high electrical conductivities and enhanced compressive properties, which are highly efficient in improving both mechanical and electrical performances of epoxy composites. Compared to those of neat epoxy, the compressive modulus, compressive strength and energy absorption of the electrically conductive GCFA/epoxy composite are significantly increased by 60%, 59% and 131%, respectively.

Electrospinning Janus Type CoO_(x)/C Nanofibers as Electrocatalysts for Oxygen Reduction Reaction

Nanofibers with unique structures and multiple components have attracted more and more attention,which could combine multi-functions in one entity.Janus-type biphasic nanofibers with unique structure can be quickly obtained by electrospinning technology.We produced CoO_(x)/C nanofibers with Janus structure by self-made side-by-side electrospinning spinneret,combined with electrospinning technology and heat treatment.CoO_(x)/C nanofibers had a large amount of graphitic carbon distributed on one half of the Janus nanofiber,and CoO_(x)/C nanoparticles were embedded in the other half of the Janus nanofiber and distributed uniformly.CoO_(x)/C acted as ORR catalysis,and graphitic carbon,pridinc-N and CoO_(x) in CoO_(x)/C had a synergistic effect on their catalytic activity.The results confirmed that CoO_(x)/C was dominated by four-electron pathway under alkaline conditions,and the Tafel slope was lower than that of commercial Pt/C catalysts.The preparation method of this work is simple and easy,the structure is controllable,and the composition is adjustable,which provides a feasible way for preparing Janus structure nanofibers with different functions.

Oil-Water Separation Performance of Electrospray Reduced Graphene Oxide Microspheres with a Local Radially Aligned and Porous Structure

Micro-size oil adsorbents are effective for the rapid remediation of special oil spills.Here,N-doped reduced graphene oxide(RGO)microspheres(ca.150µm in diameter)with a local radially aligned and porous structure are fabricated by combining electrospray-freeze-drying with thermal treatment for rapid separation of oil-water.Owing to its hydrophobic/oleophilic properties and oriented structure,the N-doped RGO microspheres achieve high capacities and fast adsorption rates for a variety of oils and organic solvents.Furthermore,excellent oil-water separation performance on floating oil/oil-water emulsions and stable cyclic adsorption capacities are obtained for the local radially aligned and porous microsphere.Therefore,N-doped RGO microspheres with the unique porous structure have the potential for the remediation of oily sewage and oil spills.

Preparation of Alum-borneol-PVP Drug-loaded Fibers by Electrospinning

The alum-borneol nanoemulsion(ABN),which combines the mineral medicine alum and the botanical medicine borneol,has been applied for approximately 40 years in the clinical treatment of burns,scalds,radiation dermatitis and shingles,and has a good curative effect.However,the current formula and dosage form of ABN pose problems of low borneol content and ease of precipitation,which greatly affects the efficacy of the drug.In this study,polyvinylpyrrolidone(PVP)was selected as a carrier mixed with different proportions of alum and borneol to produce alum-borneol-PVP fibers(ABPF)by electrospinning.The results showed that the stable system with good drug dispersion was 2:3(alum:borneol).The dissolution content of borneol from the ABPF was about 80%in 4 h,which was much higher than that of the alum-borneol liquid(ABL)and ABN.The ABPF membrane showed a more significant inhibitory effect on Staphylococcus aureus than the ABL and ABN.The composite fiber markedly increased the drug content of borneol,which was 800 times of that in ABN.The fiber had a higher solubility than the nanoemulsion in vitro,which is of great importance for the development of new forms for the clinical application of alum and borneol.

Design,Preparation and Properties of Bio-inspired Hierarchical Structure Yarns with Enhanced Thermal Insulation and Water Transfer Ability

Encouraged by the porous and stable structure of cold-resist animals’hair or feather,bio-inspired hierarchical structure yarns combining polyacrylonitrile(PAN)nanofibers and polypropylene(PP)hollow microfibers have been developed by a modified conjugate electrospinning technology.Physical cross-linking has been built to increase fibers adhesion and construct interlayer support for nanofibrous assembly.The nanofibers and hollow microfibers construct a stable porous structure with porosity of 62%,providing excellent thermal insulating ability[temperature difference(|ΔT|)between skin and yarn surface is 4.9℃]as well as good mechanical property.More interestingly,the water transfer ability(infiltrate the yarn in 10 s)of synthetic fibers has been improved greatly by the combination of thin diameter nanofibers to the yarn.It is believed that the research lays the foundation for bio-inspired engineering technology in the manufacture of thermal comfort.

A novel core-shell rifampicin/isoniazid electrospun nanofiber membrane for long time drug dissolution

Rifampicin(RIF)and isoniazid(INH)are commonly applied jointly in clinical to improve the treatment efficacy of tuberculosis.Due to the metabolism of the kidneys,most of RIF and INH would be excreted by human bodies after reaching a high drug concentration,which causes serious waste of drugs and does harm to our health.In this study,polylactic acid(PLLA)was chosen as the carrier to prepare core-shell drug-loaded nanofibers with RIF in the shell and INH in the core by coaxial electrospinning.The results showed that the average diameter of the core-shell drug-loaded fibers with an obvious core-shell structure was about 650 nm.Parts of RIF and INH in the fibers became amorphous;the rest maintained crystalline.The combination of PLLA and RIF made the fibers obvious hydrophobic and exhibited a slowly phased sustained-dissolve property during in vitro dissolution studies.The in vitro antibacterial experiments confirmed that the core-shell drug-loaded nanofibers had a favorite inhibitory effect on Staphylococcus aureus,which endowed practical medical value to the fibers.The core-shell drug-loaded nanofibers effectively separated RIF and INH,preventing the degradation of RIF caused by the direct contact of the two drugs.The slow-dissolve characteristics can maintain a relatively stable drug concentration and avoid the damage to the human body caused by the quick dissolve and rapid metabolism of drugs.The combination with coaxial electrospinning fills the gap in the core-shell system with two drugs and has great significance in the future.

Highly conductive calcium ion-reinforced MXene/sodium alginate aerogel meshes by direct ink writing for electromagnetic interference shielding and Joule heating

Although MXene sheets possess high electrical conductivity and rich surface chemistry and are well suit-able for fabricating electrically conductive nanocomposites for electromagnetic interference(EMI)shield-ing applications,it remains challenging for MXene nanocomposites to achieve tunable EMI shielding per-formances and customized geometries.Herein,an aqueous MXene/sodium alginate ink is developed to print aerogel meshes with customized geometries using a direct ink writing approach.An ion-enhanced strategy is proposed to reinforce the printed aerogel meshes by multi-level cross-linking.The resultant 3D printed aerogel mesh exhibits an ultrahigh electrical conductivity of 2.85×10^(3)S m^(−1),outstanding mechanical properties,and excellent structural stability in wet environment.More importantly,a wide range of tunable EMI shielding efficiencies from 45 to 100 dB is achieved by the structural design of the 3D printed ion-enhanced MXene/sodium alginate aerogel meshes.As a Joule heater,in addition,the printed aerogel meshes can achieve a wide temperature range of 40-135℃at low driving voltages.This work demonstrates a direct ink writing approach for the fabrication of ion-enhanced MXene/sodium al-ginate aerogel meshes with tunable EMI shielding properties and multi-functionalities for applications in many scenarios.

Constructing central hollow cylindrical reduced graphene oxide foams with vertically and radially orientated porous channels for highly efficient solar-driven water evaporation and purification

Although solar steam generation is an eco-friendly approach for desalinating seawater and purifying wastewater,there are still issues on how to improve the efficiency of solar energy utilization and accelerate the water and heat transport inside the solardriven water evaporators.Herein,we design a central hollow cylindrical reduced graphene oxide(RGO)foam with vertically and radially orientated channels as a solar steam generation device for efficient water evaporation and purification.The vertically aligned porous channels accelerate upward transport of water to the top evaporation surface,while the radially aligned porous channels facilitate water transport and heat transfer along the radial directions for fully utilizing the heat accumulated inside the central cylindrical hole of the foam.The central hole of the foam plays a highly positive role in accumulating more heat for accelerating the water evaporation,the newly generated inner sidewall resulted from the central hole can gain extra thermal energy from surrounding environment in the same way as the outer sidewall of the foam due to the surface cooling effect of the water evaporation.As a result,the vertically and radially aligned RGO foam evaporator with central hollow cylinder achieves a high solar steam generation rate of 2.32 kg·m^(−2)·h^(−1)with an exceptional energy conversion efficiency of 120.9%under 1-sun irradiation,superior to the vertically aligned RGO foam without the central hole(1.83 kg·m^(−2)·h^(−1),96.9%)because of the enhanced water and heat transfer inside the porous channels,the efficient utilization of environmental energy.