Efficient CO_(2)Reduction to Formate on CsPbI_(3) Nanocrystals Wrapped with Reduced Graphene Oxide

Transformation of greenhouse gas(CO_(2))into valuable chemicals and fuels is a promising route to address the global issues of climate change and the energy crisis.Metal halide perovskite catalysts have shown their potential in promoting CO_(2)reduction reaction(CO_(2)RR),however,their low phase stability has limited their application perspective.Herein,we present a reduced graphene oxide(rGO)wrapped CsPbI_3 perovskite nanocrystal(NC)CO_(2)RR catalyst(CsPbI_3/rGO),demonstrating enhanced stability in the aqueous electrolyte.The CsPbI_3/rGO catalyst exhibited>92%Faradaic efficiency toward formate production at a CO_(2)RR current density of~12.7 mA cm^(-2).Comprehensive characterizations revealed the superior performance of the CsPbI_3/rGO catalyst originated from the synergistic effects between the CsPbI_3 NCs and rGO,i.e.,rGO stabilized theα-CsPbI_3 phase and tuned the charge distribution,thus lowered the energy barrier for the protonation process and the formation of~*HCOO intermediate,which resulted in high CO_(2)RR selectivity toward formate.This work shows a promising strategy to rationally design robust metal halide perovskites for achieving efficient CO_(2)RR toward valuable fuels.

Vacancy engineering of oxidized Nb_(2)CTx MXenes for a biased nitrogen fixation

The artificial nitrogen(N_(2)) reduction reaction(NRR) via electrocatalysis is a newly developed methodology to produce ammonia(NH3) at ambient conditions,but faces the challenges in N_(2)activation and poor reaction selectivity.Herein,Nb-based MXenes are developed to remarkably enhance the NRR activity through the engineering of the stretched 3D structure and oxygen vacancies(VO).The theoretical studies indicate that N_(2)could be initially adsorbed on VOwith an end-on configuration,and the potential determining step might be the first hydrogenation step.The catalysts achieve an NH3production rate of 29.1 μg h^(-1)mg_(cat)^(-1)and excellent Faradic efficiency of 11.5%,surpassing other Nbbased catalysts.The selectivity of NRR is assigned to the unique structure of the catalysts,including(1) the layered graphitic structure for fast electron transfer and active site distribution,(2) the reactive VOfor N_(2)adsorption and activation,and(3) the expanded interlayer space for mass transfer.

Recent progress on the prediction of two-dimensional materials using CALYPSO

In recent years, structure design and predictions based on global optimization approach as implemented in CALYPSO software have gained great success in accelerating the discovery of novel two-dimensional(2D) materials. Here we highlight some most recent research progress on the prediction of novel 2D structures, involving elements, metal-free and metal-containing compounds using CALYPSO package. Particular emphasis will be given to those 2D materials that exhibit unique electronic and magnetic properties with great potentials for applications in novel electronics, optoelectronics,magnetronics, spintronics, and photovoltaics. Finally, we also comment on the challenges and perspectives for future discovery of multi-functional 2D materials.

Pumpkin-like MoP-MoS_(2)@Aspergillus niger spore-derived N-doped carbon heterostructure for enhanced potassium storage

Biomass-derived carbon materials are widely applied in the energy storage and conversion fields due to their rich sources,low price and environmental friendliness.Herein,a unique pumpkin-like MoPMoS_(2)@Aspergillus niger spore-derived N-doped carbon(SNC)composite has been prepared via a simple hydrothermal and subsequent phosphorization process.Interestingly,the resulting MoP-MoS_(2)@SNC well inherits the pristine morphology of spore carbon,similar to the natural pumpkin,with hollow interiors and uneven protrusions on the surface.The special structure allows it to have sufficient space to fully contact the electrolyte and greatly reduces the ion transport distance.The theory calculations further demonstrate that the formed MoP-MoS_(2)heterostructure can enhance the adsorption of K ions and electronic couplings.With these unique advantages,the MoP-MoS_(2)@SNC anode for potassium storage shows a high reversible capability of 286.2 mAh g&(-1) at 100 mA g^(-1) after 100 cycles and superior rate performance.The enhanced electrochemical performance is mainly related to the unique pumpkin-like morphology of SNC and the construction of MoP-MoS_(2)heterostructure,as well as their perfect coupling.This study provides a feasible design idea for developing green,low-cost,and high-performance electrode materials for next-generation energy storage.

Interfacial growth of N,S-codoped mesoporous carbon onto biomass-derived carbon for superior potassium-ion storage

Carbonaceous materials have been recognized as one of the most promising anode materials for potassium-ion batteries(PIBs)due to their abundant raw materials,controllable structure,superior conductivity,and good chemical inertness.However,the large radius of K ions and the low potassium content of intercalation compounds result in the sluggish storage kinetics and low reversible capacity of carbon anodes.In this work,we present a unique heteroatom-doped carbon composite(denoted as NS-MC/SC)through a facile interfacial assembly route and simple heat-treatment process,where NS-MC is well grafted onto the biomass-derived spore carbon(SC).This unique structural design endows it with abundant mesoporous channels,expanded layer spacing,and highly doped N and S.With these merits,the NS-MC/SC anode in PIBs exhibits a high reversible capacity of 350.4 mAh·g^(-1) at 100 mA·g^(-1) after 300 cycles,and an outstanding cycling stability.Besides,in-situ Raman spectra further verify the high reversibility of K ions insertion/extraction.Importantly,theoretical simulations also reveal that the N,S dual-doping is an efficient approach for improving the potassium-ion storage performance of NS-MC/SC.

Two-dimensional polarized MoSSe/MoTe2 van der Waals heterostructure: A polarization-tunable optoelectronic material

Two-dimensional (2D) heterostructures have shown great potential in advanced photovoltaics due to their restrained carrier recombination, prolonged exciton lifetime and improved light absorption. Herein, a 2D polarized heterostructure is constructed between Janus MoSSe and MoTe_(2) monolayers and is systematically investigated via first-principles calculations. Electronically, the valence band and conduction band of the MoSSe−MoTe_(2) (MoSeS−MoTe_(2)) are contributed by MoTe_(2) and MoSSe layers, respectively, and its bandgap is 0.71 (0.03) eV. A built-in electric field pointing from MoTe_(2) to MoSSe layers appears at the interface of heterostructures due to the interlayer carrier redistribution. Notably, the band alignment and built-in electric field make it a direct z-scheme heterostructure, benefiting the separation of photogenerated electron-hole pairs. Besides, the electronic structure and interlayer carrier reconstruction can be readily controlled by reversing the electric polarization of the MoSSe layer. Furthermore, the light absorption of the MoSSe/MoTe_(2) heterostructure is also improved in comparison with the separated monolayers. Consequently, in this work, a new z-scheme polarized heterostructure with polarization-controllable optoelectronic properties is designed for highly efficient optoelectronics.

Engineering active Ni-doped Co_(2)P catalyst for efficient electrooxidation coupled with hydrogen evolution

The thermodynamically favorable electrocatalytic oxidation coupled with hydrogen evolution reaction(HER)is considered as a sustainable and promising technique.Nonetheless,it remains a great challenge due to the lack of simple,cheap,highefficient electrocatalysts.Here,we successfully develop a simple and scalable electro-deposition and subsequent phosphorization route to fabricate Ni-doped Co_(2)P(Ni-Co_(2)P)nanosheets catalyst using the in-situ released Ni species from defective Ni foam as metal source.Impressively,the as-synthesized Ni-Co_(2)P catalyst exhibits excellent electrochemical 5-hydroxymethylfurfural oxidation reaction(HOR)performance with>99%2,5-furandicarboxylic acid yield and>97%Faradaic efficiency at an ultralow potential of 1.29 V vs.reversible hydrogen electrode(RHE).Experimental characterization and theoretical calculation reveal that the atomically doped Ni species can enhance the adsorption of reactant and thus lower the reaction energy barriers.By coupling the electrocatalytic HOR with HER,the employed two-electrode system using Ni-Co_(2)P and commercial Ni foam as anode and cathode,respectively,exhibits a low cell voltage of 1.53 V to drive a current density of 10 mA·cm^(−2),which is 90 mV lower than that of pure water splitting.This work provides a facile and efficient approach for the preparation of high-performance earth-abundant electrocatalysts toward the concurrent production of H_(2)and value-added chemicals.

Understanding the roles of carbon in carbon/g-C_(3)N_(4)based photocatalysts for H2 evolution

Coupling graphitic carbon nitride(CN)with carbonaceous materials is an effective strategy to improve photocatalytic performance,but the contributions of carbonaceous materials are not fully understood.Herein,a new type of carbon/CN(CCN)complex photocatalyst is synthesized with a 6-fold enhancement of H2 evolution rate compared to that of pristine CN.The role of carbon in photocatalytic H2 evolution reaction is systemically studied and it is experimentally and theoretically revealed that carbon mainly contributes to the improved capability of exciton dissociation and enhanced electric conductivity for charge transfer,leading to an increased population of photo-carriers for photocatalytic reactions.Interestingly,the enhanced light absorption originated from carbon barely generates charge carriers for H2 evolution activity.These new findings will inspire the rational design of carbon-based photocatalysts for efficient solar fuel production.

Highly sensitive,humidity-tolerant and flexible NO_(2)sensors based on nanoplate Bi_(2)Se_(3)film

Recently,two-dimension(2D)materials have fueled considerable interest in the field of gas sensing to cope urgent demands at specific scenarios.Unfortunately,the susceptibility to ambient humidity,and/or fragile operation stability always frustrate their further practicability.To overcome these drawbacks,we proposed one novel flexible gas sensor based on bismuth selenide(Bi_(2)Se_(3))nanoplates for sensitive NO_(2)detection at room temperature.The as-prepared Bi_(2)Se_(3)sensor exhibited favorable sensing performance,including remarkable NO_(2)selectivity,high response of 120%and fast response time of 81 s toward 5ppm NO_(2),an ultralow detection limit of 100 ppb,and nice stability.Besides,the excellent humidity tolerance and mechanical flexibility endowed Bi_(2)Se_(3)sensors with admirable reliability under harsh working conditions.The first-principles calculation further revealed the insights of extraordinary NO_(2)selectivity and the underlying gas-sensing mechanism.

Activating the hydrogen evolution reaction in low-dimensional carbon by partial hydrogenation: Role of the hybrid sp^(2) -sp^(3) orbital interface

Developing highly efficient catalyst for the hydrogen evolution reaction(HER)and understanding their mecha-nism is crucial for establishing the hydrogen economy.Carbon-based materials are particularly attractive as HER catalysts because of their abundance and morphological variety.Herein,using density functional theory(DFT)calculations,we propose for the first time a virtual interface consisting of sp^(2) and sp^(3) orbitals of carbon,for acti-vating the intrinsically inert low-dimensional carbon toward the HER.This hybrid orbital interface is generated by pre-adsorbed hydrogen introduced by the partial hydrogenation of these low-dimensional carbon materials(C_(60),carbon nanotubes and graphene).The pre-adsorbed hydrogen can activate adjacent carbon atoms to become active sites for the HER.The best performance among these sites is comparable to that of the commercial Pt/C catalyst.Given that the partial hydrogenation of low-dimensional carbon has been experimentally realized,our work provides a simple yet novel concept for HER catalyst design.

Single Pt atom decorated graphitic carbon nitride as an efficient photocatalyst for the hydrogenation of nitrobenzene into aniline

The hydrogenation of nitrobenzene into aniline is one of industrially important reactions, but still remains great challenge due to the lack of highly active, chemo-selective and eco-friendly catalyst. By using extensive density functional theory (DFT) calculations, herein we predict that single Pt atom decorated g-C3N4 (Pt@g-C3N4) exhibits excellent catalytic activity and selectivity for the conversion of nitrobenzene into aniline under visible light. The overall activation energy barrier for the hydrogenation of nitrobenzene on single atom Pt@g-C3N4 catalyst is even lower than that of the bare Pt(111) surface. The dissociation of N-0 bonds on single Pt atom is triggered by single hydrogen atom rather than double hydrogen atoms on the Pt(111) surface. Moreover, the Pt@g-C3N4 catalyst exhibits outstanding chemoselectivity towards the common reducible substituents, such as phenyl,-C=C,-C = C and -CHO groups during the hydrogenation. In addition, the doped single Pt atom can significantly enhance the photoconversion efficiency by broadening the light absorption of the pristine g-C3N4 to visible light region. Our results highlight an interesting and experimentally synthesized single-atom photocatalyst (Pt@g-C3N4) for efficient hydrogenation of nitrobenzene to aniline under a sustainable and green approach.

Tuning oxygen vacancies in two-dimensional iron-cobalt oxide nanosheets through hydrogenation for enhanced oxygen evolution activity

The oxygen evolution reaction （OER） represents the rate-determining step of electrocatalytic water splitting into hydrogen and oxygen. Creating oxygen vacancies and adjusting their density has proven to be an effective strategy to design high-performance OER catalysts. Herein, a hydrogenation method is applied to treat a two-dimensional （2D） iron-cobalt oxide （Fe1Co1Ox-origin）, with the purpose of tuning its oxygen vacancy density. Notably, compared with Fe1Co1Ox-origin, the iron-cobalt oxide hydrogenated at 200℃ and 2.0 MPa optimized conditions exhibits a markedly improved OER activity in 1.0 M KOH （with an overpotential 17 of 225 mV at a current density of 10 mA.cm^-2） and a rapid reaction kinetics （with a Tafel slope of 36.0 mV·dec^-1）. Moreover, the OER mass activity of the hydrogenated oxide is 1.9 times that of Fe1Co1Ox-origin at an overpotential of 350 mV. The experimental results, combined with density functional theory （DFT） calculations, reveal that the optimal control of oxygen vacancies in 2D Fe1Co1Ox via hydrogenation can improve the electronic conductivity and promote OH- adsorption onto nearby low-coordinated Co^3＋ sites, resulting in a significantly enhanced OER activity.

Leaf-inspired design of mesoporous Sb_(2)S_(3)/N-doped Ti_(3)C_(2)T_(x) composite towards fast sodium storage

Owing to excellent conductivity and abundant surface terminals,MXene-based heterostructures have been intensively investigated as energy storage materials.However,elaborate design of the structure and composition of MXene-based hybrids towards superior electrochemical performance is still challenging.Herein,we present an ingenious leaf-inspired design for preparing a unique Sb_(2)S_(3)/nitrogen-doped Ti_(3)C_(2)T_(x)MXene(L-Sb_(2)S_(3)/Ti_(3)C_(2))hybrid.In-situ TEM observations reveal that the leaflike Sb_(2)S_(3)nanoparticles with numerous mesopores can well relieve the large volume changes via an inward pore filling mechanism with only 20%outward expansion,whereas highly conductive N-doped Ti_(3)C_(2)T_(x)nanosheets can serve as the robust mechanical support to reinforce the structural integrity of the hybrid.Benefiting from the structural and constituent merits,the L-Sb_(2)S_(3)/Ti_(3)C_(2)anode fabricated exhibits a fast sodium storage behavior in terms of outstanding rate capability(339.5 mA h g^(-1)at 2,000 mA g^(-1))and high reversible capacity at high current density(358.2 mA h g^(-1)at 1,000 mA g^(-1)after 100 cycles).Electrochemical kinetic tests and theoretical simulation further manifest that the boosted electrochemical performance mainly arises from such a unique leaf-like Sb_(2)S_(3)mesoporous nanostructure with abundant active sites,and enhanced Na^(+)adsorption energy on the heterojunction formed between Sb_(2)S_(3)nanoparticles and Ti_(3)C_2)matrix.

吡嗪化石墨炔的多功能电催化作用:吡啶氮与过渡金属原子的协同效应

在同一种材料中实现高效的析氢反应(HER)、析氧反应(OER)和氧还原反应(ORR)催化活性的多功能催化剂对再生燃料电池和水分解等领域的应用具有重要意义. Pt作为目前性能最好的HER和ORR催化剂,其OER性能并不突出. Ru和IrO2虽然OER活性较高,但其HER和OER活性低于Pt催化剂.本文在单原子催化的基础上,提出了一种同时实现高效HER、OER和ORR多功能催化作用的新方案.利用吡嗪化石墨炔(PR-GDY)单层作为衬底,通过吡啶氮和锚定的过渡金属原子的协同效应,实现高效的HER、OER和ORR催化作用.量子力学第一性原理计算表明, Ni掺杂形成的Ni@PR-GDY具有较低的HER、OER和ORR的过电势,分别为-0.05, 0.29和0.38 V,在理论上接近甚至优于目前性能最好的单一功能催化剂和双功能催化剂的过电势.该结果不仅提出了一种潜在的高效三功能催化剂,同时也为多功能催化材料的设计提供了新思路.

In-situ conversion growth of carbon-coated MoS_(2)/N-doped carbon nanotubes as anodes with superior capacity retention for sodium-ion batteries

Layered structure MoS_(2) nanosheets have shown great potential for energy storage applications.However,the methodology for elaborately controllable growth of MoS_(2) onto carbonaceous matrix for promoting the electrochemical performance is highly desirable.Herein,a high-effective,all-in-one in-situ conversion growth strategy has been proposed to construct a stable sandwich-type nanostructure.The formation of the optimized C-MoS_(2)/NCNTs product undergoes a dissolution-recrystallization process,in which ultra-thin carbon layer-coated MoS_(2) nanosheets densely assembled onto the surface of polyimide(PI)derived N-doped carbon nanotubes(CNTs).Theoretical simulation reveals that MoS_(2) nanosheets possessing an expanded interlayer spacing of 0.92 nm can greatly reduce the barrier energy of Na ions mitigation.Ac-cordingly,the as-made C-MoS_(2)/NCNTs anode delivers superior cycling stability(82%capacity retention after 400 cycles at 1 A g^(−1))and rate performance(348 mAh g^(−1) at 2 A g^(−1)).The results demonstrate that the expanded MoS_(2) interlayer distance,ultrathin outer carbon coating,and N-doped CNTs matrix together accounts for the outstanding sodium storage capability for the C-MoS_(2)/NCNTs electrode.

Carbon-coated MoS_(2) nanosheets@CNTs-Ti_(3)C_(2) MXene quaternary composite with the superior rate performance for sodium-ion batteries

The exploration of advanced MoS_(2)-based electrode materials overcoming their inherent low conductivity and large volume changes is of importance for next-generation energy storage.In this work,we report a simple and high-efficient one-pot hydrothermal approach to prepare a unique and stable 1D/2D heterostructure.In the architecture,ultrathin carbon layer-coated MoS_(2) nanosheets with large expanded interlayer of 1.02 nm are vertically grown onto the Ti_(3)C_(2) MXene and cross-linked carbon nanotubes(CNTs),giving rise to a highly conductive 3D network.The interlayer expanded MoS_(2) nanosheets can greatly facilitate the Na ions/electrons transmission.Meanwhile,the N-doped 1D/2D CNTs-Ti_(3)C_(2) matrix can be used as a strong mechanical support to well relieve the large volume expansion upon cycles.As a combination result of several advantages,the developed quaternary C-MoS_(2)/CNTs-Ti_(3)C_(2) composite anode shows an excellent sodium storage performance(562 mA h g^(-1) at 100 mA g^(-1) after 200 cycles)and rate capability(475 mA h g^(-1) at 2000 mA g^(-1)).The density functional theory calculations further prove that the full combination of layer-expanded MoS_(2) nanosheets and N-doped Ti_(3)C_(2) matrix can significantly enhance the adsorption energy of Na ions,further resulting in the enhancement of sodium storage capabilities.

Organic-inorganic bismuth （lll）-based material： A lead- free, air-stable and solution-processable light-absorber beyond organolead perovskites

Methylammonium bismuth （III） iodide single crystals and films have been developed and investigated. We have further presented the first demonstration of using this organic-inorganic bismuth-based material to replace lead/tin-based perovskite materials in solution-processable solar cells. The organic-inorganic bismuth-based material has advantages of non-toxicity, ambient stability, and low-temperature solution-processability, which provides a promising solution to address the toxicity and stability challenges in organolead- and organotin-based perovskite solar cells. We also demonstrated that trivalent metal cation-based organic-inorganic hybrid materials can exhibit photovoltaic effect, which may inspire more research work on developing and applying organic-inorganic hybrid materials beyond divalent metal cations （Pb （II） and Sn （II）） for solar energy applications.

Group 14 element-based non-centrosymmetric quantum spin Hall insulators with large bulk gap

迄今为止，很多二维(2D ) 拓扑的绝缘体(TI ) 在组 14 元素的蜂房格子被认识到，但是都是 inversionsymmetric。基于第一原则的计算，这里，我们预言 2D 的一个新家庭有可观的体积的倒置不对称的 TI 从 105 兆电子伏豁开到 284 兆电子伏，在 X2GeSn (X = H， F， Cl， Br，我) 单层，为房间温度应用使他们原则上合适。转换乐队订单的重要拓扑的特征与 X = 在太古的 X2GeSn 被识别(F， Cl， Br，我) ，而 H2GeSn 在 8% 格子扩大经历重要乐队倒置。拓扑地保护的边状态与 X = 在 X2GeSn 被识别(F， Cl， Br，我) ，以及在拉紧的 H2GeSn。更重要地，这些系统的边，它展出 single-Dirac-cone 特征完全在他们的体积乐队差距的中间定位了，为无驱散的运输是理想的。因此，组 14 元素的蜂房格子为量状态的操作提供一个迷人的运动场。

Highly compact and uniform CH3NH3Sn0.5Pb0.5I3 films for efficient panchromatic planar perovskite solar cells

An efficient panchromatic planar perovskite solar cell is developed based on highly uniform,lead-reduced CH3NH3Sn0.5Pb0.5I3 perovskite films with full film-coverage on the substrates.We demonstrate here that full-coverage of the CH3NH3Sn0.5Pb0.5I3 films can be developed by a facile chlorobenzene-assisted spin-coating method.A power conversion efficiency of 7 % is achieved using low-temperature processes,which is among the best-reported performance for panchromatic planar perovskite solar cells with a light-absorption over 1,000 nm.

B-incorporated,N-doped hierarchically porous carbon nanosheets as anodes for boosted potassium storage capability

Carbonaceous nanomaterials with porous structure have become the highly promising anode materials for potassium-ion batteries(PIBs)due to their abundant resources,low-cost,and excellent conductivity.Nevertheless,the sluggish reaction kinetics and inferior cycling life caused by the large radius of K ions severely restrict their commercial development.Herein,B,N co-doped hierarchically porous carbon nanosheets(BNPC)are achieved via a facile template-assisted route,followed by a simple one-step carbonization process.The resultant BNPC possesses a unique porous structure,large surface area,and high-level B,N co-doping.The structural features endows it with remarkable potassium storage performances,which delivers a high reversible capacity(242.2 mA h/g at100 m A/g after 100 cycles),and long cycling stability(123.1 m Ah/g at 2000 m A/g and 62.9 m Ah/g at5000 mA/g after 2000 cycles,respectively).Theoretical simulations further validate that the rich B doping into N-modified carbon configuration can greatly boost the potassium storage capability of the BNPC anode.