Electrocatalytic reduction of nitrate to ammonia has become a popular approach for wastewater treatment and ammonia production. However, the development of highly efficient electrocatalysts remains a great challenge. Herein, we systematically studied the potential of InBi for nitrate reduction to ammonia (NRA) based on density functional theory (DFT) calculations. Our results reveal that InBi exhibits high activity for NRA via an O-end pathway, where the free energy evolution of all intermediates is downhill in the most favorable elementary steps. The activation of nitrate originates from the strong orbital hybridization between oxygen and indium atoms, leading to an enhanced charge transfer as well as NO 3 − adsorption. In particular, the competing hydrogen evolution reaction (HER) is effectively suppressed due to the weak adsorption of proton. Our study not only proves the great electrocatalytic potential of InBi as a novel catalyst for NRA but also points out a new way to design NRA electrocatalysts for practical applications.

Carbon materials are widely used in various industrial applications due to their outstanding stability and robustness in diverse structures, yet it remains a revolutionary and challenging task in activating carbon materials for efficient and low-cost catalysis. Herein, inspired by the successful experimental studies, we for the first-time exploited carbon nanotubes encapsulated transition metal atoms (TM@CNT) for hydrogen evolution reaction (HER) using density functional theory (DFT) calculations. The Gibbs free energy of H-C bond on pristine CNTs is too positive, which prevents the adsorption of H atoms. However, TM@CNT (TM = Fe, Co, Ni) has superior HER performance than that of the widely recognized Pt and MoS2 catalysts, benefiting from disruption of the π conjunctions and activation of the stable sp2 hybridizations between carbon atoms in CNTs. A set of metal-free catalytic surfaces with high HER activity have been developed. Meanwhile, the HER performance of graphene nanosheets loaded on the most ubiquitous facet (111) of transition metals (TM@G, TM = Fe, Co, Ni) also be calculated. However, TM@G shows lower HER activity than that of the TM@CNT, which is attributed to the large curvature of CNTs. These new findings manifest a universal strategy for carbon materials activation that will inspire the rational design of carbon-based electrocatalysts for efficient water splitting.