Vacancy-stabilized Pt/Pd bimetallic sub-nanocluster interfaces for promoting the photoconversion pathway of CO2 to CH4

Cd vacancies precisely anchor Pt/Pd sub-nanoclusters to boost interfacial electron transfer. • The vacancy-stabilized PtPd interface steers the CO 2 reduction pathway toward CH 4 . • DFT and in situ DRIFTS unveil stabilized intermediates (*CH 3 O) and suppressed CO desorption. • The optimized catalyst achieves a 119.5-fold enhancement in CH 4 yield over pristine CdS. Selective photoreduction of CO 2 to deeply hydrogenated products remains challenging due to the competitive formation of CO and insufficient surface hydrogenation capability. Herein, a vacancy-stabilized Pt/Pd sub-nanoclusters interface is constructed on a Cd-based semiconductor to preferentially facilitate surface reaction pathways toward CH 4 production. Cd vacancies are proposed to serve as preferential anchoring and electronic modulation centers, promoting the formation of Pt/Pd interfacial sites with strong metal support interactions, and facilitating electron transfer. Multiple characterization techniques confirm that the Pt/Pd sub-naoclusters interface is preferentially stabilized at vacancy-rich regions and exhibits pronounced electronic coupling. In situ DRIFTS reveals the emergence of key hydrogenated intermediates on the Pt/Pd interfacial surface, indicating a surface-mediated pathway shift from CO desorption to deep hydrogenation. Density functional theory (DFT) calculations further confirm enhanced CO 2 activation and stabilization of hydrogenation intermediates at the vacancy-coupled Pt/Pd sub-nanoclusters. Compared to pristine CdS and Cd 1-x S, the Pt/Pd-Cd 1-x S photocatalyst achieved 119.5-fold and 14.9-fold enhancements in CH 4 yield, respectively. Consequently, the engineered interfacial surface achieves a significantly enhanced methane selectivity during CO 2 photoreduction. This work highlights the important role of vacancy-mediated dual metal interfaces in promoting surface reaction pathways and provides new insights into the rational design of selective CO 2 photoreduction catalysts from a surface science perspective. Download: Download high-res image (169KB) Download: Download full-size image