Ruthenium-Engineered Active Hydrogen Dynamics in Cobalt Hydroxide: Enabling Enhanced Ammonia Synthesis and Photothermally Assisted Zn-Nitrite Battery

The electrocatalytic nitrite reduction reaction (NO 2 RR) offers a viable route for converting nitrite-contaminated wastewater into high-value ammonia (NH 3 ) under mild conditions. However, its practical application is impeded by limited selectivity and slow kinetics, primarily stemming from an insufficient supply of active hydrogen (*H). Herein, we rationally design and fabricate a ruthenium nanoparticle-decorated cobalt hydroxide nanowire (Ru–Co(OH) 2 ) electrocatalyst for enhanced NO 2 RR, achieving an ammonia yield rate of 7.71 mg h –1 cm –2 and a Faradaic efficiency (FE) of 93.1% at −0.5 V vs RHE. Operando spectroscopic studies and theoretical calculations reveal that the incorporation of Ru significantly strengthens interfacial water adsorption and lowers the water dissociation energy barrier. Moreover, by leveraging the localized surface plasmon resonance (LSPR) of Ru, a photothermally assisted Zn-NO 2 – battery is exploited, which exhibits substantially increased power density under near-infrared (NIR) light illumination. This work highlights the potential of heterointerfacial electrocatalysts as a promising platform for advancing sustainable ammonia synthesis and nitrite remediation.