Photo-assisted Rechargeable Metal Batteries for Energy Conversion and Storage

Solar cells hold a function of photovoltaic conversion,while rechargeable metal batteries have an advantage of high energy storage.The conventional charge mode of batteries is made based on complete utilization of electric energy.The combination of solar cells and rechargeable metal batteries brings a new opportunity for the development of photo-assisted rechargeable batteries,in which the solar energy can be utilized to partially achieve photo-charging with or without external electrical bias.This review highlights the working mechanism and structure design of photo-assisted rechargeable metal batteries according to the characteristics of rechargeable metal batteries and advantage of the photovoltaic technology.In particular,the recent advances are introduced for photo-assisted rechargeable batteries based on light-weight metal anodes,including metal lithium,metal sodium,and metal zinc.The working features of the integrated devices are also discussed for energy saving under photo-assisted charging mode.Finally,a future outlook is provided for further improving the performance of photoassisted rechargeable metal batteries.

A p-n WO_(3)/SnSe_(2) Heterojunction for Efficient Photo-assisted Electrocatalysis of the Oxygen Evolution Reaction

Water splitting is important to the conversion and storage of renewable energy,but slow kinetics of the oxygen evolution reaction(OER)greatly limits its utility.Here,under visible light illumination,the p-n WO_(3)/SnSe_(2)(WS)heterojunction significantly activates OER catalysis of CoFe-layered double hydroxide(CF)/carbon nanotubes(CNTs).Specifically,the catalyst achieves an overpotential of 224 mV at 10 mA cm^(-2)and a small Tafel slope of 47 mV dec^(-1),superior to RuO_(2)and most previously reported transition metal-based OER catalysts.The p-n WS heterojunction shows strong light absorption to produce photogenerated carriers.The photogenerated holes are trapped by CF to suppresses the charge recombination and facilitate charge transfer,which accelerates OER kinetics and boost the activity for the OER.This work highlights the possibility of using heterojunctions to activate OER catalysis and advances the design of energy-efficient catalysts for water oxidation systems using solar energy.

Nanodots and microwires of ZrO_2 grown on LaAlO_3 by photo-assisted metal–organic chemical vapor deposition

ZrO_2 nanodots are successfully prepared on LaAlO_3（LAO）（100） substrates by photo-assisted metal-organic chemical vapor deposition（MOCVD）. It is indicated that the sizes and densities of ZrO_2 nanodots are controllable by modulating the growth temperature, oxygen partial pressure, and growth time. Meanwhile, the microwires are observed on the surfaces of substrates. It is found that there is an obvious competitive relationship between the nanodots and the microwires. In a growth temperature range from 500℃ to 660℃, the microwires turn longest and widest at 600℃, but in contrast, the nanodots grow into the smallest diameter at 600℃. This phenomenon could be illustrated by the energy barrier, decomposition rate of Zr（tmhd）_4, and mobility of atoms. In addition, growth time or oxygen partial pressure also affects the competitive relationship between the nanodots and the microwires. With increasing oxygen partial pressure from 451 Pa to 75_2 Pa,the microwires gradually grow larger while the nanodots become smaller. To further achieve the controllable growth, the coarsening effect of ZrO_2 is modified by varying the growth time, and the experimental results show that the coarsening effect of microwires is higher than that of nanodots by increasing the growth time to quickly minimize ZrO_2 energy density.

GaN hexagonal pyramids formed by a photo-assisted chemical etching method

A series of experiments were conducted to systematically study the effects of etching conditions on GaN by a con-venient photo-assisted chemical （PAC） etching method. The solution concentration has an evident influence on the surface morphology of GaN and the optimal solution concentrations for GaN hexagonal pyramids have been identified. GaN with hexagonal pyramids have higher crystal quality and tensile strain relaxation compared with as-grown GaN. A detailed anal- ysis about evolution of the size, density and optical property of GaN hexagonal pyramids is described as a function of light intensity. The intensity of photoluminescence spectra of GaN etched with hexagonal pyramids significantly increases compared to that of as-grown GaN due to multiple scattering events, high quality GaN with pyramids and the Bragg effect.

Interface and border trapping effects in normally-off Al2O3/AlGaN/GaN MOS-HEMTs with different post-etch surface treatments

Trapping effect in normally-off Al2O3/AlGaN/GaN metal–oxide–semiconductor (MOS) high-electron-mobility transistors (MOS-HEMTs) with post-etch surface treatment was studied in this paper. Diffusion-controlled interface oxidation treatment and wet etch process were adopted to improve the interface quality of MOS-HEMTs. With capacitance–voltage (C–V) measurement, the density of interface and border traps were calculated to be 1.13 × 10^12 cm^−2 and 6.35 × 10^12 cm^−2, effectively reduced by 27% and 14% compared to controlled devices, respectively. Furthermore, the state density distribution of border traps with large activation energy was analyzed using photo-assisted C–V measurement. It is found that irradiation of monochromatic light results in negative shift of C–V curves, which indicates the electron emission process from border traps. The experimental results reveals that the major border traps have an activation energy about 3.29 eV and the change of post-etch surface treatment process has little effect on this major activation energy.

3D layer-by-layer amorphous MoS_(x) assembled from[Mo_(3)S_(13)]^(2-)clusters for efficient removal of tetracycline:Synergy of adsorption and photo-assisted PMS activation

Peroxymonosulfate(PMS)activation and photocatalysis are effective technologies to remove organic pollutants,but the adsorption effect of the catalyst is usually unheeded in degradation process.Herein,a bifunctional catalyst of amorphous MoS_(x)(a-MoS_(x))with 3D layer-by-layer superstructure was synthesized by assembling basic active units[Mo_(3)S_(13)]^(2-)of MoS_(2).The large interlayer spacing and high exposure of active sites render a-MoS_(x)to have excellent synergy of adsorption and photo-assisted PMS activation for tetracycline(TC)degradation.Experiments and DFT calculation show that TC can be efficiently enriched on a-MoS_(x)by pore filling,π-πinteraction,hydrogen bonding and high adsorption energy.Subsequently,PMS can be quickly activated through electron transfer with a-MoS_(x),resulting in high TC degradation efficiency of 96.6%within 20 min.In addition,the synergistic mechanism of adsorption and photo-assisted PMS activation was explored,and the degradation pathway of TC was expounded.This work is inspirational for constructing bifunctional catalysts with superior synergistic adsorption and catalytic capabilities to remove refractory organic pollutants in water.

Method of evaluating interface traps in Al2O3/AlGaN/GaN high electron mobility transistors

In this paper, the interface states of the AlGaN/GaN metal–insulator–semiconductor(MIS) high electron mobility transistors(HEMTs) with an Al2 O3 gate dielectric are systematically evaluated. By frequency-dependent capacitance and conductance measurements, trap density and time constant at Al2 O3/AlGaN and AlGaN/GaN interface are determined.The experimental results reveal that the density of trap states and the activation energy at the Al2 O3/AlGaN interface are much higher than at the AlGaN/GaN interface. The photo-assisted capacitance-voltage measurements are performed to characterize the deep-level traps located near mid-gap at the Al2 O3/AlGaN interface, which indicates that a density of deep-level traps is lower than the density of the shallow-level states.

Oxygen vacancy-rich MoO_(3)nanorods as photocatalysts for photo-assisted Li-O_(2) batteries

Photo-assisted lithium-oxygen(Li-O_(2))batteries have been developed as a new system to reduce a large overpotential in the Li-O_(2)batteries.However,constructing an optimized photocatalyst is still a challenge to achieve broad light absorption and a low recombined rate of photoexcited electrons and holes.Herein,oxygen vacancy-rich molybdenum trioxide(MoO_(3-x))nanorods are employed as photocatalysts to accelerate kinetics of cathode reactions in the photo-assisted Li-O_(2)batteries.Oxygen vacancies on the MoO_(3-x)nanorods can not only increase light-harvesting capability but also improve electrochemical activity for the cathode reactions.Under illumination,the photoexcited electrons and holes are effectively separated on the MoO_(3-x)nanorods.During discharging,activated O2 is reduced to Li_(2)O_(2)by the photoexcited electrons from the MoO_(3-x)nanorods.The photoexcited holes can promote the decomposition of Li_(2)O_(2)during subsequent charging.Accordingly,the photo-assisted Li-O_(2)batteries with the MoO_(3-x)nanorods deliver an ultralow overpotential of 0.22 V,considerable rate capability,and good reversibility.We think that this work could give a reference for the exploitation and application of the photocatalysts in the photo-assisted Li-O_(2)batteries.

Two-dimensional TiO_(2)(001)nanosheets as an effective photo-assisted recyclable sensor for the electrochemical detection of bisphenol A

Electrochemical detection is an efficient method for the detection of Bisphenol A(BPA).Herein,a sensitive photo-electrochemical sensor based on two-dimensional(2 D)TiO_(2)(001)nanosheets was fabricated and then used for BPA electrochemical detection.Upon light irradiation,the 2 D TiO_(2)(001)nanosheets electrode provided a lower detection limit of BPA detection compared with an ambient electrochemical determination.The low detection limit is^5.37 nmol/L(S/N=3).Furthermore,profiting from the photoelectric characteristics,the 2 D TiO_(2)(001)nanosheets electrode exhibits a nice regeneration prope rty.After 45 min of light irradiation,the electrochemical signal was regenerated from14.7%to 82.9%of the original signal at the 6th cycle.This is attributed to the non-selective·OH mediation produced by the 2 D TiO_(2)(001)nanosheets mineralizing anodic polymeric products and resuming surface reactive sites.This investigation indicates that photo-assistance is an efficient method to improve the electrochemical sensor for detecting BPA in water environments.

Photo-assisted electrochemical hydrogen evolution by plasmonic Ag nanoparticle/nanorod heterogeneity

Transition metal sulfide-based hydrogen evolution electrocatalysts still lag in catalytic activity due to the zero-deviated free energy of*H adsorption.Plasmonic metals bridge the gap between light utilization and plasmon-mediated redox reactions for substantially enhanced electrocatalytic activity.In this work,a strategic broadband light utilization heterostructure,composed of two distinct Ag nanostructures(discontinuous Ag nanorods and monodispersed nanoparticles),is achieved through in situ sulfurization and metal leaching.The heterostructure benefits the electrocatalytic hydrogen evolution reactivity thanks to the localized surface plasmon resonance induced hot electrons injection and inter-gap electric fields revealed by the finite-difference time-domain simulation.Experimentally,the prudent heterostructured catalyst exhibits a significantly improved overpotential(at 10 mA cm−2)from 151 to 95 mV along with a Tafel slope from 74 to 45 mV dec−1 toward hydrogen evolution.Significantly,this instructional study sheds light on the design of hybrid photo-assisted electrocatalysts with cooperative effect of solar energy toward sustainable electrocatalysis.

Photo-assisted decoration of Ag-Pt nanoparticles on Si photocathodes for reducing overpotential toward enhanced photoelectrochemical water splitting

Developing new catalysts to decorate photoelectrodes has been widely used to enhance the performance of photoelectrochemical(PEC)cells.However,the high cost,complex synthesis,and poor stability of catalyst decoration strongly hinder its practical application.Here,we report a facile and low-cost decoration of Ag-Pt nanoparticles(Ag-Pt NPs)on Si photocathodes with TiO_(2)/Ti sacrificial overlayers.Such a decoration does not rely on any metallic-ion precursor solution since it is formed automatically via galvanic replacement reactions during PEC measurements;that is,Ti is displaced by Ag^(+)and Pt^(2+)ions,which are from the employed reference and counter electrodes,respectively.The as-decorated Ag-Pt NPs are verified to significantly enhance the hydrogen evolution reduction kinetics without substantially degrading the optical performance of Si photocathodes.Owing to optoelectronic advantages,the overpotential required to maintain a photocurrent density of 10 mA cm(under AM1.5 G illumination)is reduced from-0.8 V_(RHE)(for the bare planar Si photocathode)to-0.1 V_(RHE)(for the planar Si photocathode with Ag-Pt NP decoration).Moreover,a further anodic shift(to 0 V_(RHE))is visible for the Si nanowire array photocathode with Ag-Pt NP decoration,along with high long-term stability of the PEC response in acidic and neutral electrolytes.This study opens a new opportunity for the photo-assisted decoration of various alloy NPs on the morphology-varying photoelectrodes with different applications.

Photo-assisted Deposited Titanium Dioxide Film and the Enhancement of Its Photocatalytic Water Splitting Activity

Photo-assisted deposited method is often employed in the metal-organic chemical vapor deposition whose ion source is organic compounds. It has been proved to increase the deposition rate and improve the crystallinity of the films. We demonstrate a photo-assisted sputtering deposited method which is used to prepare high quality TiO_(2) films. The crystallinity of the films is improved by the photo assistance without changing the morphology. And the structural and optical properties remain the same. The photo-assisted deposited TiO_(2) film shows a H_(2) evolution rate of 1.62 μmol·cm^(-2)·h^(-1) that is about twice more than that of the pristine TiO_(2) film. It is found the Mott-Schottky effect responds for the photocatalytic activity. Photo-assisted deposited films show an enhanced photocatalytic activity due to the reduction of interface recombination and the high efficiency in the transferring of photo-generated carriers.

Photo-assisted charging of carbon fiber paper-supported CeO_(2)/MnO_(2) heterojunction and its long-lasting capacitance enhancement in dark

It is important to develop green and sustainable approaches to enhance electrochemical charge storage efficiencies.Herein,a two-step in-situ growth process was developed to fabricate carbon fiber paper-supported CeO_(2)/MnO_(2) composite(CeO_(2)/MnO_(2)–CFP)as a binder-free photoelectrode for the photo-assisted electrochemical charge storage.The formation of CeO_(2)/MnO_(2) type II heterojunction largely enhanced the separation efficiency of photo-generated charge carriers,resulting in a substantially enhanced photo-assisted charging capability of~20%.Furthermore,it retained a large part of its photo-enhanced capacitance(~56%)in dark even after the illumination was off for 12 h,which could be attributed to its slow release of stored photo-generated electrons from its specific band structure to avoid their reaction with O_(2) in dark.This study proposed the design principles for supercapacitors with both the photo-assisted charging capability and its long-lasting retainment in dark,which may be readily applied to other pseudocapacitive materials to better utilize solar energy.

Sol-gel transition effect based on konjac glucomannan thermosensitive hydrogel for photo-assisted uranium extraction

Exploiting the intelligent photocatalysts capable of phase separation provides a promising solution to the removal of uranium,which is expected to solve the difficulty in separation and the poor selectivity of traditional photocatalysts in carbonate-containing uranium wastewater.In this paper,theγ-FeOOH/konjac glucomannan grafted with phenolic hydroxyl groups/poly-N-isopropylacrylamide(γ-FeOOH/KGM(Ga)/PNIPAM)thermosensitive hydrogel is proposed as the photocatalysts for extracting uranium from carbonate-containing uranium wastewater.The dynamic phase transformation is demonstrated to confirm the arbitrary transition ofγ-FeOOH/KGM(Ga)/PNIPAM thermosensitive hydrogel from a dispersed state with a high specific surface area at low temperatures to a stable aggregated state at high temperatures.Notably,theγ-FeOOH/KGM(Ga)/PNIPAM thermosensitive hydrogel achieves a remarkably high rate of 92.3%in the removal of uranium from the wastewater containing carbonates and maintains the efficiency of uranium removal from uranium mine wastewater at over 90%.Relying on electron spin resonance and free radical capture experiment,we reveal the adsorption-reduction-nucleation-crystalliza tion mechanism of uranium onγ-FeOOH/KGM(Ga)/PNIPAM thermosensitive hydrogel.Overall,this strategy provides a promising solution to treating uranium-contaminated wastewater,showing a massive potential in water purification.

The applications of semiconductor materials in air batteries

Air batteries are promising energy storage technologies that have gained continuous attraction due to their high energy densities.At present,investigations on anodes of air batteries are usually focused on various metals such as Li,Zn,Al.In contrast,the semiconductor anodes like Si and Ge are less investigated.Si-air battery possesses a high theoretical energy density and Ge-air battery has a high actual power density and ideal safety.Besides anodes,air cathodes where oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)are also the key components in air batteries.To further promote the discharging performance and facilitate energy conversion/storage,semiconductor materials have been introduced in electrochemical cells like Li-O_(2) and Zn-air batteries.This review briefly summarizes semiconductor materials utilized in various air batteries,including the progress of Si-air and Ge-air batteries and recent advances in semiconductor cathodes catalysts.Finally,the remaining challenges and further perspective are discussed.

Carbon dots modified Ti_(3)C_(2)T_(x)-based fibrous supercapacitor with photo-enhanced capacitance

The energy crisis has always been a widely concerned problem. It is an urgent need for green and renewable energy technologies to achieve sustainable development, and the photo-assisted charging energy storage devices provide a new way to realize the sustainable utilization of solar energy. Here, we fabricated a photo-assisted charging fibrous supercapacitor (NM2P1) with Ti_(3)C_(2)T_(x)-based hybrid fibre modified by nitrogen-doped carbon dots (NCDs). The NM2P1 fibre provides a volumetric capacitance of 1,445 F·cm^(−3) (630 F·g^(−1)) at 10 A·cm^(−3) under photo-assisted charging, which increases by 35.9% than that of dark condition (1,063 F·cm^(−3)/464 F·g^(−1)). Furthermore, the NM2P1 fibrous supercapacitor device shows that the maximum volumetric energy density and volumetric power density are 18.75 mWh·cm^(−3) and 8,382 mW·cm^(−3). Notably, the transient photovoltage (TPV) test was used to further confirm that NCDs as a photosensitizer enhance the light absorption capacity and faster charge transfer kinetics of NM2P1 fibre. This work directly exploits solar energy to improve the overall performance of supercapacitor, which opens up opportunities for the utilization of renewable energy and the development of photosensitive energy equipment.

NiCo_(2)O_(4)/BiOCl/Bi_(24)O_(31)Br_(10) ternary Z-scheme heterojunction enhance peroxymonosulfate activation under visible light: Catalyst synthesis and reaction mechanism

The Z-scheme heterostructure for photocatalyst can effectively prolong the lifetime of photogenerated carriers and retain a higher conduction/valence band position,promoting the synergistic coupling of photocatalysis and peroxymonosulfate(PMS) activation.In order to fully utilize the luminous energy and realize the efficient activation of PMS,this work achieved successful construction of NiCo_(2)O_(4)/BiOCl/Bi_(24)O_(31)Br_(10) ternary Z-scheme heterojunction by simultaneously synthesizing BiOCl and NiCo_(2)O_(4) with NiCl_(2) and CoCl_(2) as the precursors.The intercalated BiOCl could serve as a carrier migration ladder to further achieve the spatial separation of electron-hole pairs,so that the oxidation and reduction processes separately occurred in different regions.Compared with the reported catalysts,the as-prepared composites exhibited the enhanced removal efficiency for tetracycline hydrochloride(TCH) in the visible light/PMS system,with a degradation efficiency of 85.30%in 2 min,and possessed good stability.Z-scheme heterojunction was shown to be beneficial for maximizing the superiority of photo-assisted Fenton-like reaction system.The experimental and characterization results confirmed that both non-radicals(^(1)O_(2)) and radicals(SO_(5)^(·-) and SO_(4)^(·-)) were involved in the reaction process and the SO_(5)^(·-)generated by the oxidation of PMS played a crucial role in the TCH degradation.The possible reaction mechanism was finally proposed.This study provided new insight into the Z-scheme heterostructure to promote the photo-assisted Fenton-like reaction.

通过锚定钯纳米颗粒在CsPbBr_(3)钙钛矿纳米晶体上从而增强光催化CO_(2)还原

最近,全无机铯铅溴(CsPbX_(3)(X=Cl,Br,I))钙钛矿纳米晶体被广泛应用于光催化CO_(2)还原(CO_(2)RR)领域.但是,由于纯CsPbX_(3)纳米晶体内部载流子辐射复合严重,所以精心设计基于CsPbX_(3)纳米晶体的异质结构对于分离载流子和实现高效的CO_(2)RR是非常重要的.本文中,我们介绍了利用光辅助的方法将Pd纳米颗粒锚定在CsPbX_(3)纳米晶体上.利用此方法所制备的CsPbBr_(3)@Pd纳米晶体通过在CsPbBr_(3)/Pd界面处构建肖特基结从而促进了载流子的分离并抑制了辐射复合.第一性原理计算表明:在CO_(2)RR过程中,CsPbBr_(3)@Pd纳米晶体比纯CsPbX_(3)纳米晶体具有更低的能量势垒.当CsPbBr_(3)@Pd纳米晶体被用作CO_(2)RR催化剂时,电子消耗速率高达46.2μmol g^(-1)h^(-1),是纯CsPbX_(3)纳米晶体作为光催化剂时电子消耗速率的4.8倍.这项工作不仅介绍了一种利用光辅助将钯纳米颗粒锚定在CsPbX_(3)纳米晶体上的方法,而且还证明了CsPbBr_(3)@Pd纳米晶体在光催化CO_(2)还原领域的巨大潜能.

Photoexcited singlet enhanced oxygen reduction reaction with high selectivity on the photosensitizer/layered double hydroxides nanocomposite

Oxygen reduction reaction(ORR)plays a pivotal role in advanced electrochemical energy conversion devices.However,the ORR conversion efficiency is extremely limited.The major obstacles originate from the adsorption and activation of O_(2)on the electrode surface.A novel nanocomposite catalyst,photosensitizers(PS)meso-tetraphenylporphyrin iron(III)chloride(FePcCl)/NiCoFe-layered double hydroxides(NiCoFe-LDHs)is designed in this study.Herein,owing to excellent oxygen molecules activation ability and remarkable illumination absorption feature,FePcCl/NiCoFe-LDHs is employed to uncover the relationship between the intrinsic ORR activity and PS behaviour.Interestingly,the reaction mechanism of singlet 1O_(2)is proposed owing to the combination of electrochemical ORR catalysed via LDHs and PS.The boosted cathodic ORR properties exhibit singlet 1O_(2)dependent response arising from the synergistic effect to selectively produce active intermediates in alkaline medium.This work imparts the promising new mechanism about the high 4-electron ORR selectivity via material design,which will guide the development of photo-assisted energy conversion devices.

External field–assisted batteries toward performance improvement

Rechargeable batteries are essential for the increased demand for energy storage technologies due to their ability to adapt intermittent renewable energies into electric devices,such as electric vehicles.To boost the battery performance,applying external fields to assist the electrochemical process has been developed and exhibits significant merits in energy efficiency and cycle stability enhancement.This perspective focuses on recent advances in the development of external field–assisted battery technologies,including photo-assisted,magnetic field–assisted,sound field–assisted,and multiple field–assisted.The workingmechanisms of external field–assisted batteries and their challenges and opportunities are highlighted.