Maximized Synergistic Interaction of Pd Single Atoms with CuCo2S4 Nanosheets Catalysts for High-Efficiency Photocatalytic H2 Production and O2 Reduction via Enhanced Charge Separation and Transfer

Abstract

The photocatalytic conversion of naturally abundant molecules into value-added products is a key solution for sustainable development, addressing energy and environmental challenges. This study introduces a simple, eco-friendly one-step hydrothermal method for synthesizing atomically dispersed Pd single-atom catalysts (SACs) on CuCo2S4 semiconductor nanosheets, designed for these applications. The structure of PdSA‒CuCo2S4 is investigated by aberration-corrected transmission electron microscopy and X-ray absorption fine structure (XAFS) spectroscopy. The novel synthesis process ensures strong coordination between the Pd SAs and sulfur ions on the CuCo2S4 nanosheet surface, reducing overall charge transfer resistance, and making them ideal for photogenerated electron capture based on asymmetric charge density distribution. The 0.10PdSA‒CuCo2S4 SAC (0.1 wt.% Pd loading) achieves a visible-light-driven H2 production rate of 39550 µmol g‒1 h‒1 with a notable apparent quantum efficiency of 15.57% (at 420 nm wavelength) and high stability. The same Pd SAC can facilitate the reduction of O2 to H2O2 via photocatalytic oxygen reduction reaction (ORR), achieving an O2‒to‒H2O2 production rate of 19200 µmol g‒1 h‒1 and negligible decomposition of the produced H2O2. The proposed strategy herein offers new insights to facilitate the enhanced photocatalytic H2 and H2O2 production by Pd SAs on CuCo2S4 semiconductor nanosheets by overcoming mass-transfer limitations.