Self-assembled S-scheme In_(2.77)S_(4)/K^(+)-doped g-C_(3)N_(4)photocatalyst with selective O_(2) reduction pathway for efficient H_(2)O_(2) production using water and air

The development of an efficient artificial H_(2)O_(2) photosynthesis system is a challenging work using H_(2)O and O_(2) as starting materials.Herein,3D In_(2.77)S_(4) nanoflower precursor was in-situ deposited on K^(+)-doped g-C_(3)N_(4)(KCN)nanosheets using a solvothermal method,then In_(2.77)S_(4)/KCN(IS/KCN)het-erojunction with an intimate interface was obtained after a calcination process.The investigation shows that the photocatalytic H_(2)O_(2) production rate of 50IS/KCN can reach up to 1.36 mmol g^(-1)h^(-1)without any sacrificial reagents under visible light irradiation,which is 9.2 times and 4.1 times higher than that of KCN and In_(2.77)S_(4)/respectively.The enhanced activity of the above composite can be mainly attributed to the S-scheme charge transfer route between KCN and In_(2.77)S_(4) according to density functional theory calculations,electron paramagnetic resonance and free radical capture tests,leading to an expanded light response range and rapid charge separation at their interface,as well as preserving the active electrons and holes for H_(2)O_(2) production.Besides,the unique 3D nanostructure and surface hydrophobicity of IS/KCN facilitate the diffusion and transportation of O_(2) around the active centers,the energy barriers of O_(2) protonation and H_(2)O_(2) desorption steps are ef-fectively reduced over the composite.In addition,this system also exhibits excellent light harvesting ability and stability.This work provides a potential strategy to explore a sustainable H_(2)O_(2) photo-synthesis pathway through the design of heterojunctions with intimate interfaces and desired reac-tion thermodynamics and kinetics.

Novel S‐scheme 2D/2D BiOBr/g‐C_(3)N_(4)heterojunctions with enhanced photocatalytic activity

The design and construction of heterojunction photocatalysts,which possess a staggered energy band structure and appropriate interfacial contact,is an effective way to achieve outstanding photocatalytic performance.In this study,2D/2D BiOBr/g‐C_(3)N_(4)heterojunctions were successfully obtained by a convenient in situ self‐assembly route.Under simulated sunlight irradiation,99%of RhB(10 mg·L–1,100 mL)was efficiently degraded by 1.5‐BiOBr/g‐C_(3)N_(4)within 30 min,which is better than the performance of both BiOBr and g‐C_(3)N_(4),and it has superior stability.In addition,the composite also exhibits enhanced photocatalytic activity for H2 production.The enhanced activity can be attributed to the intimate interface contact,the larger surface area,and the highly efficient separation of photoinduced electron–hole pairs.Based on the experimental results,a novel S‐scheme model was proposed to illuminate the transfer process of charge carriers.This study presents a simple way to develop novel step‐scheme photocatalysts for environmental and related applications.

2D mesoporous ultrathin Cd0.5Zn0.5S nanosheet:Fabrication mechanism and application potential for photocatalytic H2 evolution

Two-dimensional mesoporous ultrathin Cd0.5Zn0.5S nanosheets with a thickness of~1.5 nm were fabricated using a multistep chemical transformation strategy involving inorganic–organic hybrid ZnS-ethylenediamine(denoted as ZnS(en)0.5)as a hard template.Inorganic–organic hybrid ZnS(en)0.5,Cd0.5Zn0.5S(en)x,and Cd0.5Zn0.5S nanosheets were sequentially fabricated,and their transformation processes were analyzed in detail.The fabricated Cd0.5Zn0.5S nanosheets exhibited high photocatalytic hydrogen evolution reaction activity in the presence of a sacrificial agent.The Cd0.5Zn0.5S nanosheets exhibited remarkably high H2 production activity of~1395μmol∙h^−1∙g^−1 in pure water with no co-catalyst,which is the highest value reported thus far for bare photocatalysts,to the best of our knowledge.The high activity of these nanosheets is attributed to their distinct nanostructure(e.g.,short transfer distance of photoinduced charge carriers,large number of unsaturated surface atoms,and large surface area).Moreover,ternary NiCo2S4 nanoparticles were employed to facilitate the charge separation and enhance the surface kinetics of H2 evolution.The H2 production rate reached~62.2 and~2436μmol∙h^−1∙g^−1 in triethanolamine and pure water,respectively,over the NiCo2S4/Cd0.5Zn0.5S heterojunctions.The result indicated that the Schottky junction was critical to the enhanced activity.The proposed method can be used for fabricating other highly efficient CdZnS-based photocatalysts for solar-energy conversion or other applications.

Enhanced photocatalytic H_2 production over dual-cocatalyst-modified g-C_3N_4 heterojunctions

Ag nanoparticles (NPs) were deposited on the surface of g-C3N4 (CN) by an in situ calcination method. NiS was successfully loaded onto the composites by a hydrothermal method. The results showed that the 10 wt%-NiS/1.0 wt%-Ag/CN composite exhibits excellent photocatalytic H2 generation performance under solar-light irradiation. An H2 production rate of 9.728 mmol·g^-1·h^-1 was achieved, which is 10.82-, 3.45-, and 2.77-times higher than those of pure g-C3N4, 10 wt%-NiS/CN, and 1.0 wt%-Ag/CN composites, respectively. This enhanced photocatalytic H2 generation can be ascribed to the co-decoration of Ag and NiS on the surface of g-C3N4, which efficiently improves light harvesting capacity, photogenerated charge carrier separation, and photocatalytic H2 production kinetics. Thus, this study demonstrates an effective strategy for constructing excellent g-C3N4-related composite photocatalysts for H2 production by using different co-catalysts.

UV-VIS-NIR-induced extraordinary H2 evolution over W_(18)O_(49)/Cd_(0.5)Zn_(0.5)S:Surface plasmon effect coupled with S-scheme charge transfer

In this work,a novel plasmon-assisted UV-vis-NIR-driven W_(18)O_(49)/Cd_(0.5)Zn_(0.5)S heterostructure photocatalyst was obtained by a facile ultrasonic-assisted electrostatic self-assembly strategy.The hybrid exhibits extraordinary H2 evolution activity of 147.7 mmol·g^(-1)·h^(-1) at room temperature due to the efficient charge separation and expanded light absorption.Our investigation shows that the unique Step-scheme(S-scheme)charge transfer and the‘hot electron’injection are both responsible for the extraordinary H2 evolution process,depending on the wavelength of the incident light.Moreover,by accelerating the surface reaction kinetics,the activity can be further elevated to 306.1 mmol·g^(-1)·h^(-1),accompanied by a high apparent quantum yield of 45.3% at 365±7.5 nm.This work provides us a potential strategy for the highly efficient conversion of the solar energy by elaborately combining a nonstoichiometric ratio plasmonic material with an appropriate active photocatalyst.

Bi_(2)WO_(6)/AgInS_(2)S-scheme heterojunction:Efficient photodegradation of organic pollutant and toxicity evaluation

Constructing of heterojunction was identified as a feasible way to improve photocatalytic activity of pho-tocatalyst.In this work,a n-p type Bi_(2)WO_(6)/AgInS_(2)S-scheme heterojunction was successfully prepared for organic pollutants degradation.This Bi_(2)WO_(6)/AgInS_(2)S-scheme heterojunction exhibited much higher pho-tocatalytic activity towards Rhodamine B(92.24%,expose to visible light for 60 min),norfloxacin(81.73%,expose to visible light for 90 min)and levofloxacin(87.46%,expose to visible light for 90 min)than pure Bi_(2)WO_(6)and pure AgInS_(2).Toxicity analysis indicated the low environmental toxicity of Rhodamine B degradation intermediates for Rye seeds and Sudangrass seeds germination and growth.Mechanism study displayed that AgInS_(2)and Bi_(2)WO_(6)work as the primary photocatalyst to form·O_(2)−and ·OH,respectively.The improved photocatalytic activity of the Bi_(2)WO_(6)/AgInS_(2)S-scheme heterojunction was due to the im-proved light response range and intensified carrier separation capability.Additionally,a S-scheme charge transfer mechanism including multiple charge transfer channels was proposed.This work could provide an effective strategy for organic pollutants degradation in wastewater.

S-scheme regulated Ni_(2)P-NiS/twinned Mn_(0.5)Cd_(0.5)S hetero-homojunctions for efficient photocatalytic H_(2)evolution

Effective bulk phase and surface charge separation is critical for charge utilization during the photo-catalytic energy conversion process.In this work,the ternary Ni_(2)P-NiS/twinned Mn_(0.5)Cd_(0.5)S(T-MCS)nanohybrids were successfully constructed via combining Ni_(2)P-NiS with T-MCS solid solution for visible light photocatalytic H_(2)evolution.T-MCS is composed of zinc blende Mn_(0.5)Cd_(0.5)S(ZB-MCS)and wurtzite Mn_(0.5)Cd_(0.5)S(WZ-MCS)and those two alternatively arranged crystal phases endow T-MCS with excellent bulk phase charge separation performance for the slight energy level difference between ZB-MCS and WZ-MCS.S-scheme carriers transfer route between NiS and T-MCS can accelerate the interfacial charge separation and retain the active electrons and holes,meanwhile,co-catalyst Ni_(2)P as electron receiver and proton reduction center can further optimize the H_(2)evolution reaction kinetics based on the surface Schottky barrier effect.The above-formed homo-heterojunctions can establish multiple charge transfer channels in the bulk phase of T-MCS and interface of T-MCS and Ni_(2)P-NiS.Under the synergistic effect of twinned homojunction,S-scheme heterojunction,and Schottky barrier,the ternary Ni_(2)P-NiS/T-MCS com-posite manifested an H_(2)production rate of 122.5 mmol h^(-1)g^(-1),which was 1.33,1.24,and 2.58 times higher than those of the NiS/T-MCS(92.4 mmol h^(-1)g^(-1)),Ni_(2)P/T-MCS(98.4 mmol h^(-1)g^(-1)),and T-MCS(47.5 mmol h^(-1)g^(-1)),respectively.This work demonstrates a promising strategy to develop efficient sul-fides photocatalyst toward targeted solar-driven H_(2)evolution through homo-heterojunction engineering.

rGO空间限域生长超薄In_(2)S_(3)纳米片用于构建高效准一维Sb_(2)Se_(3)基异质结光阴极

硒化锑(Sb_(2)Se_(3))属于窄带隙半导体材料,具有良好的光吸收特性,已逐渐应用于光电催化领域.独特的一维(Sb_(4)Se_(6))_(n)带状结构单元连接方式,使其载流子传输具有高度各向异性.本文通过气相输运沉积法和原位水热法成功构建了还原氧化石墨烯(rGO)修饰的准一维Sb_(2)Se_(3)@In_(2)S_(3)光陷阱异质结.研究结果表明,在rGO空间限域效应下,原位生长的非层状In_(2)S_(3)纳米片厚度从30 nm减小到10 nm,显著增加了光电极的电化学活性比表面积,进一步增强了光陷阱纳米结构对光的捕获能力.rGO和超薄In_(2)S_(3)纳米片共同修饰的准一维毛刷状Sb_(2)Se_(3)@In_(2)S_(3)-rGO纳米棒光电极在0 V(相对于可逆氢电极)的外加偏压下,光电流密度可达1.169 m A cm^(-2),约是Sb_(2)Se_(3)@In_(2)S_(3)和单体Sb_(2)Se_(3)的2倍和16倍,且稳定性良好,在中性条件下平均产氢速率为16.59μmol cm^(-2)h^(-1).实验结果和理论计算均表明,Ⅱ型异质结电荷传输方式是其光电化学增强的物理机制.以上工作为设计基于rGO修饰的复合光电极用于光电化学领域的研究提供了崭新的思路.

K2HPO4-mediated Photocatalytic H_(2)Production over NiCoP/RP Heterojunction

In this work,bimetallic NiCoP nanoparticles(NPs)were firstly prepared by a solvothermal method using red phosphorus(RP)as P source,and it was combined with RP nanosheets via a physical grinding process.Investigation indicates that NiCoP has better charge transfer ability and faster H_(2)releasing kinetics than the corresponding single metal phosphides alone.6 wt%NiCoP/RP exhibits an excellent H_(2)evolution activity in 20 vol.%triethanol-amine/water solution under a 300W Xe-lamp irradiation,and the corresponding H_(2)production rate is 1535.6μmol·g^(-1)·h^(-1),which is 7.4,3.2 and 2.6 times higher than those of pure RP,6 wt%Co_(2)P/RP and 6 wt%Ni_(2)P/RP,respectively.In addition,we demonstrate that K_(2)HPO_(4)can further enhance the H_(2)evolution kinetics by inducing a new H^(+)reduction path,when appropriate K_(2)HPO_(4)is introduced into the reaction solution.The H_(2)production rate of 6 wt%NiCoP/RP is boosted from 1535.6 to 2793.9μmol·g^(-1)·h^(-1) due to the easier combination between H^(+)and electrons with the assistance of HPO_(4)^(2-).It is 13.4 times higher than that of pure RP.This work demonstrates that bimetallic phosphides with suitable electrolytes can greatly enhance the photocatalytic H_(2)evolution efficiency.

Preface to Solar Photocatalysis

Solar energy is the most important clean and renewable energy in the world.However,the unpredictability,seasonal variation day and night,uneven distribution and low energy density limit its practical application.Photocatalysis technology has a very broad application prospect in solving energy and environmental problems.