Nanostructured hybrid catalysts empower the artificial leaf for solar-driven ammonia production from nitrate

Abstract

Converting solar energy into chemicals and fuels through photoelectrocatalytic (PEC) process is challenging but holds significant potential for advancing sustainable development. Here we introduce an innovative system to realize solar-driven NH₃ production from waste nitrate by nano-structured top layer (NSTL) hybrid catalysts modified commercial Si absorber, to bridge the gap from fundamental understanding to the process engineering. Specifically, we employ a rationally designed Si/Cu-NSTL/Co(OH)₂ ternary photocathode featuring a Schottky barrier contact enabling optimized photo-carrier transport pathways and a beneficial co-adsorption configuration of *NO₃–H₂O moieties. This photocathode exhibits the best-known performance in the literature for the PEC conversion of NO₃ to NH₃, boasting an onset potential of approximately 1 V_RHE and a remarkable faradaic efficiency of nearly 100%. Building upon these findings, we develop the first large-scale unbiased PEC device (an artificial leaf) capable of simultaneously producing NH₃ and valorizing biomass, achieving a solar utilization efficiency of approximately 4%. Its scalability and practical feasibility have been further validated through rigorous outdoor testing with an assembled tandem device array. The process techno-economic assessment shows compelling economic viability of this technology across diverse application scenarios in NH₃ production, resulting in substantial savings of fossil fuel and a reduction of CO₂ emissions. We anticipate that this work will serve as a valuable resource for the design of next-generation photoelectrodes and devices, bringing us one step closer to realizing standalone solar-to-sustainable chemical applications.