Surface local strain and diatomic iron doping synergistically promote the plasmonic photoelectrochemical nitrogen reduction reaction

Utilizing single/dual atom catalysts as well as the crystallographic plane effect to promote the nitrogen reduction reaction (NRR) has attracted extensive attention. However, there are few works to combine the two effects with the surface plasmon resonance effect based on the first-principles periodic slab models. Our calculated results can be summarized as three points. First, we investigated the adsorption Gibbs free energy (ΔG) of *N2 and *NNH on Au(100), Au(110), and Au(111) facets with single or dual Fe atoms doped. The strongest end-on and side-on adsorption occur at single and dimer Fe atoms doped Au(100) surfaces, respectively. More importantly, the N2 side-on adsorption configuration significantly reduces the ΔG of the first hydrogenation step. Second, we investigated the reason why there is a lower adsorption ΔG for the N2 side-on adsorption on dimer-Fe-doped Au(100). It was discovered that the interatomic distance of the Fe dimer exhibits a strong correlation with adsorption strength. When the Fe dimer is doped on the Au(100) surface, the dimer will relax due to local strain, enabling a stronger N2 side-on adsorption. Finally, we compared the photon absorption capacity between side-on and end-on nitrogen adsorption configurations, revealing that the latter exhibits enhanced light absorption capability at lower photon energies and across broader wavelength ranges. This theoretical research highlights the superiority of the N2 side-on adsorption configuration in plasmonic photoelectrochemical NRR and shows the influence of surface local strain and dynamic relaxation for side-on adsorption, which could be referenced to design efficient side-on adsorption catalysts.