Selective Hydrogen Production Enabled by WN Plasmon-Mediated Formic Acid Adsorption Reconfiguration

Hydrogen serves as a critical solar-to-fuel energy vector, with formic acid (FA) presenting unique advantages as a liquid organic hydrogen carrier due to its high hydrogen content and ambient-phase stability. However, competitive dehydrogenation (H2 + CO2) and dehydration (CO + H2O) pathways during FA decomposition have hindered achieving >90% selectivity. Here, we demonstrate precise control over FA adsorption geometry through interfacial engineering by anchoring plasmonic tungsten nitride (WN) cocatalysts onto CdS hollow spheres (WN/CdS). This modification reconfigures FA adsorption from H-terminal to O-coordination dominance, shifting the activation pathway of FA from initial C–H protonation to O–H cleavage. Consequently, dehydrogenation is steered toward 92.5% H2 selectivity. Plasmon–phonon coupling elevates the localized temperature to 90.4 °C within the catalyst system, while the barrier-free ohmic contact enables ultrafast electron migration to the WN. Photogenerated electrons accumulated on WN synergize with intrinsic surface electrons to generate energetic hot carriers, effectively facilitating FA dehydrogenation via lowered activation barriers. The resultant WN/CdS achieves a high H2 generation of 19.4 mmol h–1 g–1. This study proposes a photon–plasmon synergistic strategy for selective chemical bond cleavage in hydrogen carriers, thereby establishing a groundbreaking paradigm for high-efficiency, solar-driven hydrogen production.