Ni-NCDs promoted photocatalytic benzylamine oxidation coupled hydrogen production in Cu-In-Zn-S/WO3·H2O Z-scheme heterojunction

Abstract

The construction of Z-scheme heterojunction is important for efficient photocatalytic organic oxidation coupled hydrogen production. However, current methods suffer from poor synergy of charge extraction and surface reactions. In this study, we combined Cu-In-Zn-S (CIZS) quantum dots with WO3·H2O (WO) nanosheets to form a Z-scheme heterojunction, which was further modified with bifunctional N-doped carbon dots (NCDs) to improve charge extraction and abundant Ni sites for hydrogen evolution. The unique 0D/2D/0D CIZS/WO/Ni-NCDs heterojunction resulted in a hydrogen production rate of 4.261 mmol g−1 h−1, with ascorbic acid, 8.06 times higher than that of CIZS. In addition, the selectivity of N-benzylidenebenzylamine from benzylamine oxidation reaction has been increased from 31.65 % to 73.34 %. This improvement can be attributed to the efficient charge separation, transfer, and surface reactions accelerated by the multifunctional Ni-NCDs. A series of photoelectrochemical tests and radical scavenging experiments confirmed the Z-scheme photocatalytic process and the important roles of superoxide radicals and holes. Photo-induced electrocatalysis tests further confirmed the accelerated hydrogen evolution reaction in the presence of Ni-NCDs. Furthermore, time-resolved photoluminescence test demonstrated that the synergies of NCDs and Ni significantly extended the charge carrier lifetime. These findings provide valuable insights into efficient hydrogen production through the modulation of Z-scheme heterojunctions using bifunctional metal-carbon dots.