Regulating Localized Proton Delivery in CuCo-LDH@TiO₂ Heterojunctions for Selective Photocatalytic Nitrate Hydrogenation

Successive hydrogenation steps require a local supply of proton equivalents, but making water-derived hydrogen available at nitrate-reduction sites remains difficult. Here, CuCo-LDH supported on anatase TiO₂ nanosheets (CuCo-LDH@TNS) is constructed to couple nitrate reduction with water/peroxide chemistry and HCHO oxidation.

The optimized nominal 3% CuCo-LDH@TNS catalyst gives 94.86 ± 0.66% nitrate conversion and nearly quantitative NH₄⁺ selectivity. Spectroscopic and isotope measurements, together with product analysis and electronic-structure calculations, support a proposed interfacial proton-equivalent relay. HCHO consumes oxidation equivalents and forms HCOOH/formate, while water remains the primary hydrogen reservoir under the tested conditions.