Interfacial Chemical Bond‐Modulated Z‐Scheme Charge Transfer for Efficient Photoelectrochemical Water Splitting

Abstract

The Z‐scheme heterojunction has great potential in photoelectrochemical (PEC) water splitting due to its unique charge‐carrier migration pathway, superior carrier separation efficiency, and high redox capacity, but how to regulate the Z‐scheme charge transfer at the nanometric interface of heterostructures still remains a big challenge. Herein, InOCd bond is rationally introduced at the interface between ZnIn2S4 nanosheets and CdS nanoparticles through a facile cation exchange reaction, which successfully converts the previously reported type II band structure to a direct Z‐scheme heterojunction (ZnIn2S4/CdS) as confirmed by various characterizations. Density functional theory calculation reveals that the InOCd interfacial chemical bond significantly uplifts the Fermi level of ZnIn2S4 and CdS, inverts the interfacial band bending direction, thus resulting in the formation of Z‐scheme heterojunction. Moreover, an amorphous ZnO overlayer is deposited to eliminate the surface defects and accelerate the surface reaction kinetics. Benefiting from the superior charge separation efficiency and high redox ability originating from the Z‐scheme structure, the optimum ZnIn2S4/CdS/ZnO photoanode exhibits a dramatically enhanced PEC performance with low onset potential (−0.03 V vs reversible hydrogen electrode, VRHE) and large photocurrent of 3.48 mA cm−2 at 1.23 VRHE, which is about 21.75 times that of pristine ZnIn2S4.

Interfacial chemical bond and internal electric field modulated Z-scheme Sv-ZnIn2S4/MoSe2 photocatalyst for efficient hydrogen evolution

“…The work function (ɸ) is an important nature for reflecting the escaping ability of free electron from Fermi level (E f ) to vacuum level 45 . To investigate the mechanism for the excellent photocatalytic performance of S v -ZIS/MoSe 2 , the ultraviolet photoelectron spectroscopy (UPS) with He I as the excitation source was conducted.…”

Photocatalytic Z‐Scheme Overall Water Splitting: Recent Advances in Theory and Experiments

“…For example, the ln‐O‐Cd bond has been introduced at the interface between CdS and ZnIn 2 S 4 nanosheets via a cation exchange method. [ 198 ] As a result, the type‐II band structure was successfully converted to Z‐scheme. To confirm the role of ln‐O‐Cd in the Z‐scheme formation, the DFT calculation has been performed.…”

Incorporation of Sulfate Anions and Sulfur Vacancies in ZnIn2S4 Photoanode for Enhanced Photoelectrochemical Water Splitting

“…[6] However, due to its severe bulk carrier recombination, unfavorable carrier transportation, and sluggish surface OER dynamics, the PEC performance of bare ZnIn 2 S 4 photoanode is still not satisfactory.Various strategies have been developed to enhance the PEC performance of ZnIn 2 S 4 , such as morphology engineering, constructing heterojunctions, and coating surface co-catalysts, etc. [7][8][9] Among them, decorating surface cocatalysts has been considered as an effective strategy to promote surface water oxidation kinetics of pristine ZnIn 2 S 4 . However, the integration of water-oxidation cocatalysts with PEC photoanodes has been limited to metal-based materials, such Co-Pi, FeCoO x , and FeOOH.…”