Cd_0.5Zn_0.5S-Based Catalysts:Structure Regulation And Photocatalytic H₂ Evolution

Photocatalytic hydrogen production is considered as one of the most promising strategies to solve the global energy shortage and achieve the carbon neutrality goal.The development of efficient and stable photocatalytic materials is essential to enhance the efficiency of photocatalytic hydrogen production.CdxZn1-xS is a typical n-type ternary metal sulfide semiconductor with tunable band gap and strong visible-light response ability,which has promising applications in photocatalytic water splitting for hydrogen production.However,the fast photogenerated carrier recombination and sluggish surface reaction kinetics of intrinsic CdxZn1-xS greatly limit its hydrogen evolution activity.In this paper,we focus on the structure-activity relationship between structural modulation and photocatalytic activity of CdxZn1xS.We aim to improve the photogenerated charges separation efficiency and surface reaction kinetics of CdxZn1-xS by the strategies such as atomic doping,defect modulation and heterogeneous interface construction to achieve significant improvement in the photocatalytic performance of CdxZn1-xS-based materials.The main contents are summarized as follows:(1)Cd0.5Zn0.5S lattice anchored Pt single atoms build strong interactions to promote photocatalytic hydrogen evolution through modulation of electronic structure:Pt single atoms are stabilized in the Cd0.5Zn0.5S lattice through the Pt-S3 coordination configuration,which acts as an electron capture center to induce rapid carrier separation and improve the utilization efficiency of photogenerated electrons.The strong d-p orbital hybridization of the Pt-S coordination bond endows significant stability to the lattice-doped Pt sites,while the H*adsorption/desorption kinetics of the S sites are optimized by adjusting the surface electronic structure,increasing the density of hydrogen evolution active sites.The lattice doped Pt single atoms significantly enhanced the photocatalytic hydrogen evolution activity of Cd0.5Zn0.5S by modulating the energy band structure,improving the charge separation efficiency,and lowering the reaction energy barrier.(2)Cu doping induces self-adapting S vacancies reconstruct the Cd0.5Zn0.5S surface to boost photocatalytic hydrogen evolution by optimizing the reaction kinetics:Cu doping induced Cd0.5Zn0.5S lattice distortion generated surface S vacancies.Cu sites as hole traps combined with S vacancies as electron traps synergistically modulate the regional separation and migration of surface charges in Cd0.5Zn0.5S,which significantly prolong the photogenerated carrier lifetime by suppressing recombination.The introduction of doped Cu and S vacancies weakened the interaction of the low-coordinated metal with the surrounding S atoms,leading to a decrease in the charge density of the S sites and achieving an enhancement in the adsorption/desorption of H*.Cu doping-induced surface reconfiguration achieves enhanced photocatalytic hydrogen evolution activity of Cd0.5Zn0.5S by optimizing the separation,transport,and consumption of photogenerated charges.(3)Ultrathin Ti3C2Tx-modified S-vacancy-rich Cd0.5Zn0.5S promotes photocatalytic hydrogen evolution by constructing enhanced heterogeneous interfaces:S vacancies as electron traps enhance the separation of photogenerated electrons from holes in Cd0.5Zn0.5S.The tight 2D/2D interface constructed by the coupled ultrathin monolayer Ti2C3Tx provides a short diffusion channel for the transfer of photogenerated carriers,while the strong electronic interactions between the interfaces promote the fast electron transport and utilization.The high specific surface area of Ti2C3Tx provides abundant active sites for the hydrogen evolution reaction.S vacancies in concert with ultrathin Ti3C2Tx co-catalysts achieve increased photocatalytic hydrogen evolution activity of Cd0.5Zn0.5S by enhancing the charge separation and migration efficiency.