Sulphur vacancy defects engineered metal sulfides for amended photo(electro)catalytic water splitting: A review

Vacancy engineering in metal sulfides has garnered enormous attention from researchers because of their outstanding ability to modulate the optical and physiochemical properties of photocatalysts.Typically,in the case of sulfides,the catalytic activity is drastically hindered by the quick reassembly of excitons and the photocorrosion effect.Hence designing and generating S-vacancies in metal sulfides has emerged as a potential strategy for attaining adequate water splitting to generate H_(2) and O_(2) because of the simulta-neous improvement in the optoelectronic features.However,developing efficient catalysts that manifest optimal photo(electro)catalytic performance for large-scale applicability remains challenging.Therefore,it is of utmost interest to explore the insightful features of creating S-vacancy and study their impact on catalytic performance.This review article aims to comprehensively highlight the roles of S-vacancy in sulfides for amended overall water-splitting activity.The photocatalytic features of S-vacancies modulated metal sulfides are deliberated,followed by various advanced synthetic and characterization techniques for effectual generation and identification of vacancy defects.The specific aspects of S-vacancies in refin-ing the optical absorption range charge carrier dynamics,and photoinduced surface chemical reactions are critically examined for overall water splitting applications.Finally,the vouchsafing outlooks and op-portunities confronting the defect-engineered(S-vacancy)metal sulfides-based photocatalysts have been summarized.

Surface defect engineering of metal oxides photocatalyst for energy application and water treatment

Despite metal oxides offer excellent characteristics in the field of photocatalysis,they often suffer from charge carrier recombination as well as limited visible response,which indeed reduce the charge kinetics process and ultimately reduce the photocatalytic output.Defect engineering is a sophisticated technique to manufacture defects and alter the geometric structure and chemical environment of the host.The present study provides an all-inclusive outline of recent developments on the classification of metal oxide defects based on the dimensions of a host crystal lattice.Precisely,surface modification of metal oxides through 0D(point),1D(line),2D(planar),and 3D(volume)defects with their subsequent mechanism and impact on photocatalytic performance are presented.By wisely amending the morphology(cores along with the shells)and electronic structure of metal oxide photocatalysts(TiO_(2),ZnO,Bi_(2)O_(3),Fe_(2)O_(4) etc.)through different attuned and veritable approaches,their photocatalytic activity can be substantially improved.Optimal studies on defect engineering not only expose the altered physicochemical features but also modulate the electron-hole pair dynamics,stability,and active radical production for various photoredox reactions.Altered atomic,as well as electronic configuration,facilitated a photocatalyst material to have different optical features,adsorption properties along with improved carrier transfer as well as isolation rate.Thus,the systematic exploration of photocatalytic rudiments of defect rich metal oxide for various applications such as H_(2) evolution,CO_(2) reduction,pollutant degradation,and bacterial disinfection could bring significant research advancement in this field.