Constructing charge transfer channel between dopants and oxygen vacancies for enhanced visible-light-driven water oxidation

Photocatalytic water oxidation is a crucial step in water splitting,but is generally restricted by the slow kinetics.Therefore,it is necessary to develop high-performance water oxidation photocatalysts.Herein,the Fe-doped Bi2WO6 nanosheets with oxygen vacancies(OVs)were synthesized for enhanced photocatalytic water oxidation efficiency,showing a synergistic effect between Fe dopants and OVs.When a molar fraction of 2%Fe was doped into the Bi2WO6 nanosheets,the visible-light-driven photocatalytic oxygen evolution rate was increased up to 131.3μmol·h^(-1)·g_(cat)^(-1)under ambient conditions,which was more than 3 times that of pure Bi2WO6 nanosheets.The proper doping concentration of Fe could promote the formation of OVs and at the same time modulate the band structure of catalysts,especially the position of the valence band maximum(VBM),leading to effective visible-light absorption and enhanced oxidizing ability of photogenerated holes.With ameliorated localized electron distribution,fast charge transfer channel emerged between the OVs and adjacent metal atoms,which accelerated the charge carrier transfer and promoted the separation of photoexcited electrons and holes.This work provides feasible approaches for designing efficient two-dimensional semiconductor water oxidation photocatalysts that could utilize visible-light,which will make more use of solar energy.

Construction of atomic-level charge transfer channel in Bi_(12)O_(17)C_(l2)/MXene heterojunctions for improved visible-light photocatalytic performance

Exploring efficient co-catalysts to accurately steer the charge separation of semiconductor photocatalysts is highly desired yet remains challenging.Here,we tackle the significant challenge by in situ growing the Bi_(12)O_(17)C_(l2)photocatalyst onto two-dimensional(2D)Cl-terminated Ti_(3)C_(2)MXene to construct 2D/2D heterojunction of Bi_(12)O_(17)C_(l2)and Ti_(3)C_(2).Firstly,2D few-layered Ti_(3)C_(2)MXene with chlorine groups has been successfully syn-thesized by Lewis acidic etching strategy with subsequent ultrasonic exfoliation.The grafting of chlorine terminations on the surface of MXene serves as nucleating centers and growth platform,resulting in the formation of strong interfacial bonds(Bi-Cl-Ti)between Bi_(12)O_(17)C_(l2)and Ti_(3)C_(2).These strong bonds can facilitate the separation and transfer of photo-generated charge carriers between Bi_(12)O_(17)C_(l2)photocatalyst and Ti_(3)C_(2)cocatalyst.As expec-ted,the photocatalytic degradation rate of Bi_(12)O_(17)C_(l2)/Ti_(3)C_(2)hybrids is 9.7 times higher than that of bare Bi_(12)O_(17)C_(l2)nanosheets.This work not only exhibits a new design concept to effectively steer the charge separation for photocatalysis,but also gives a reference for constructing efficient MXene-based photocatalytic systems.

Boosting interfacial S-scheme charge transfer and photocatalytic H_(2)-production activity of 1D/2D WO_(3)/g-C_(3)N_(4)heterojunction by molecular benzene-rings integration

A novel benzene-ring engineered 1D/2D WO_(3)/g-C_(3)N_(4)S-scheme photocatalyst(BCNW)was rationally de-signed and successfully synthesized by the electrostatic self-assembly method.Experimental and Density Functional Theory results reveal that the integration of molecular benzene-ring in the framework of g-C_(3)N_(4)can not only narrow its bandgap and accelerate charge separation by forming a mid-state at the top of its valence band but more importantly open up a new additional bridge for speeding up the interfacial S-scheme charge transfer in BCNW.Benefitting from those multiple positive effects of benzene-ring inte-gration,as expected,BCNW S-scheme photocatalysts show superior photocatalytic H_(2)-production activity and reach 2971μmol h^(-1)g^(-1)under visible-light illumination,which is 3.35 times WO_(3)/g-C_(3)N_(4)S-scheme photocatalyst without benzene-ring integration.This work supplies an innovative strategy for the design of a high-efficiency S-scheme photocatalytic system by constructing a facile and additional molecular charge transfer channel at the interface.