Dipole-polarized Cu–Ni atomic interfaces for synergistic enhancement and steering of overall nitrogen photofixation

Abstract

Enabling the oxidation of ammonia (NH₃), a product of nitrogen (N₂) reduction, to nitric acid (HNO₃) can boost the economic value of overall N₂ photofixation. In this work, we constructed a Cu doped NiO@C nanosheets photocatalyst with dipole polarization effect, achieving efficient overall N₂ photofixation (N₂ → NH₃ → HNO₃) with a relatively high proportion of NO₃⁻ (92.3 %). Mechanistic studies reveal that the band structure modulation of photocatalyst and thus enhanced the oxidation capacity, further significantly promoted the NH₃ → HNO₃ pathway and increased the proportion of NO₃⁻ in the overall N₂ photofixation products. The local polarization brought along the Cu-Ni atomic interface, which promoted photo-excited charge transfer process, enhanced N₂ absorption/activation capability and promoted the N₂ → NH₃ pathway. First-principles density functional theory (DFT) calculations demonstrate that the Cu doping strategy reduce the N₂ reduction reaction (NRR) energy barrier. This work provides an approach for optimizing the overall N₂ photofixation through band structure modulation and dipole polarization effect.