Surface assembly of cobalt species for simultaneous acceleration of interfacial charge separation and catalytic reactions on Cd0.9Zn0.1S photocatalyst

Abstract

Although photocatalytic water splitting has excellent potential for converting solar energy into chemical energy, the challenging charge separation process and sluggish surface catalytic reactions significantly limit progress in solar energy conversion using semiconductor photocatalysts. Herein, we demonstrate a feasible strategy involving the surface assembly of cobalt oxide species (CoOx) on a visible-light-responsive Cd0.9Zn0.1S (CZS) photocatalyst to fabricate a hierarchical CZS@CoOx heterostructure. The unique hierarchical structure effectively accelerates the directional transfer of photogenerated charges, reducing charge recombination through the smooth interfacial heterojunction between CZS and CoOx, as evidenced by photoluminescence (PL) spectroscopy and various electrochemical characterizations. The surface cobalt species on the CZS material also act as efficient cocatalysts for photocatalytic hydrogen production, with activity even higher than that of noble metals. The well-defined CZS@CoOx heterostructure not only enhances the interfacial separation of photoinduced charges, but also improves surface catalytic reactions. This leads to superior photocatalytic performances, with an apparent quantum efficiency of 20% at 420 nm for visible-light-driven hydrogen generation, which is one of the highest quantum efficiencies measured among noble-metal-free photocatalysts. Our work presents a potential pathway for controlling complex charge separation and catalytic reaction processes in photocatalysis, guiding the practical development of artificial photocatalysts for successful transformation of solar to chemical energy.