Nitrogen-triggered plasmonic bifunctionality in ruthenium/titanium oxynitride Schottky catalyst for energized hydrazine-seawater hydrogen production

Abstract

Plasmon-coupled hydrazine-seawater electrolysis emerges as an advanced hydrogen generation approach characterized by enhanced product efficiency and renewable utilization. Though the integration of plasmonic effects with bifunctional catalysts promises to revolutionize system design, the design of such catalysts with plasmonic bifunctionality remains a huge challenge. Our work breaks new ground by employing nitrogen as a “molecular switch” to trigger plasmonic bifunctionality in ruthenium/titanium oxynitride (Ru/TiNO_0.6), achieving intrinsically and plasmon-energized hydrogen evolution reaction (overpotential: 13.5 ​mV) and hydrazine oxidation reaction (overpotential: 222.3 ​mV). The plasmonic two-electrode system demonstrates remarkable performance enhancement, boosting current density by 34.6% (127.5 ​→ ​171.6 ​mA ​cm⁻² at 0.2V) with maintaining near 100% selective conversion to H₂/N₂. Through advanced characterization and theoretical analysis, we decode nitrogen's triple role: it narrows band gap of substrate and enhances both photoelectronic and photothermal effects; it enhances Mott-Schottky effects to generate metastable amorphous Ru species, and induces interface charge polarization with creating built-in electric fields that synergistically lower activation barriers. These concerted effects yield optimal hydrogen adsorption energetics (ΔG_∗H) while facilitating ∗N₂H₃ intermediate formation and shift of rate determining step, establishing a new paradigm for plasmon-driven bifunctional electrocatalysis.