Single Nb atom modified anatase TiO2(110) for efficient electrocatalytic nitrogen reduction reaction

Abstract

We report the theory-guided design of anatase-supported Nb catalysts for electrochemical N 2 reduction reaction (NRR). Theoretical calculations predict that Nb atoms deliver multi-functional enhancement toward the NRR when incorporated in an anatase TiO 2 (110) catalyst: (1) decreasing the band gap and inducing electrons to promote the conductivity of TiO 2 (110); (2) suppressing the undesired competitive hydrogen evolution reaction; (3) activating the inert Ti sites for N 2 adsorption; (4) enabling fast charge transfer between ∗NNH and the TiO 2 (110) surface; and (5) reducing the energy barrier of the potential-determining ∗N 2 → ∗NNH step, further facilitating NH 3 formation. As a result, our Nb-TiO 2 (110) catalyst exhibits superior activity and selectivity for the NRR, which affords an NH 3 production rate of about 21.3 μg h −1 mg cat −1 and NH 3 faradaic efficiency of ∼9.2% at −0.5 V (versus reversible hydrogen electrode). This study provides insights for the rational design of efficient electrocatalysts for the NRR. • Nb single-atom-decorated TiO 2 (110) facilitates nitrogen reduction reaction (NRR) • TiO 2 (110) is more active than TiO 2 (101) for NRR • Nb-TiO 2 (110) delivers an NH 3 production rate of ∼21.3 μg h −1 mg cat −1 • Single Nb atom modified anatase TiO 2 (110) for efficient electrocatalytic nitrogen reduction reaction An electrochemical N 2 reduction reaction (NRR) that can be powered by electricity generated from renewable sources has recently gained heightened research interest, providing a promising alternative to the conventional Haber-Bosch process. Current major research efforts are being devoted to the design and development of advanced electrocatalysts to enhance the efficiency of NRR. Herein, guided by density functional theory calculations that predict the cooperative effect of Nb and anatase TiO 2 (110) in promoting electrocatalytic NRR performance, we successfully synthesize TiO 2 single crystals with selectively exposed (110) facets, supplemented with Nb atomic loading, which exhibited remarkable performance for NRR, achieving an NH 3 production rate of ∼21.3 μg h −1 mg cat −1 at −0.5 V (versus reversible hydrogen electrode). Ammonia is extensively used in industry, agriculture, and energy storage. Currently, the industrial synthesis of ammonia predominantly still relies on the energy- and capital-intensive Haber-Bosch (HB) process. Electrochemical N 2 reduction reaction (NRR) provides a renewable and distributed route for ammonia production. To boost the NRR, the development of electrocatalysts is key. Herein, we design and synthesize Nb single-atom-decorated anatase TiO 2 (110) for enhanced NRR, affording an NH 3 production rate of ∼21.3 μg h −1 mg cat −1 .