Dual-plasma enhanced 2D/2D/2D g-C₃N₄/Pd/MoO_3-x S-scheme heterojunction for high-selectivity photocatalytic CO2 reduction

The localized surface plasmon resonance (LSPR) effect has shown significant progress in enhancing the efficiency of light absorption and separating photogenerated carriers. Herein, the dual-plasma enhanced 2D/2D/2D gC3N4/Pd/MoO3-x (CPM) S-scheme heterojunction photocatalysts were synthesized using the method of hydrothermal and electrostatic self-assembly for high-selectivity photocatalytic reduction of CO2 to produce CO. The dual LSPR effect of MoO3-x and ultrathin Pd nanosheets synergistically broadened the optical response range of the CPM composites and successfully improved the photocatalytic activity and near-infrared (NIR) performance. The optimized CPM-30 photocatalysts exhibited CO yields of 18.55 mu mol g-1 with a selectivity of 96.3%. In addition, the CO yield reached 3.92 mu mol g-1 after 4 h of NIR light photoirradiation. The electron spin resonance (ESR) and ultraviolet photoelectron spectroscopy (UPS) tests showed that the S-scheme heterojunctions were constructed by coupling g-C3N4/Pd nanosheets and MoO3-x. This work will provide a reference for improving product selectivity through the design of two-dimensional composites and the utilization of plasma materials.