Symmetry-Breaking <i>p</i>-Block Antimony Single Atoms Trigger N-Bridged Titanium Sites for Electrocatalytic Nitrogen Reduction with High Efficiency.

Gu, Hongfei; Li, Jiani; Niu, Xiangfu; Lin, Jie; Chen, Li-Wei; Zhang, Zedong; Shi, Ziqian; Sun, Zhiyi et al. · ACS Nano · 2023

basic_science · Level V

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Abstract

The electrochemical nitrogen reduction reaction (eNRR) under mild conditions emerges as a promising approach to produce ammonia (NH<sub>3</sub>) compared to the typical Haber-Bosch process. Herein, we design an asymmetrically coordinated <i>p</i>-block antimony single-atom catalyst immobilized on nitrogen-doped Ti<sub>3</sub>C<sub>2</sub>T<sub><i>x</i></sub> (Sb SA/N-Ti<sub>3</sub>C<sub>2</sub>T<sub><i>x</i></sub>) for eNRR, which exhibits ultrahigh NH<sub>3</sub> yield (108.3 μg h<sup>-1</sup> mg<sub>cat</sub><sup>-1</sup>) and excellent Faradaic efficiency (41.2%) at -0.3 V vs RHE. Complementary <i>in situ</i> spectroscopies with theoretical calculations reveal that the nitrogen-bridged two titanium atoms triggered by an adjacent asymmetrical Sb-N<sub>1</sub>C<sub>2</sub> moiety act as the active sites for facilitating the protonation of the rate-determining step from *N<sub>2</sub> to *N<sub>2</sub>H and the kinetic conversion of key intermediates during eNRR. Moreover, the introduction of Sb-N<sub>1</sub>C<sub>2</sub> promotes the formation of oxygen vacancies to expose more titanium sites. This work presents a strategy for single-atom-decorated ultrathin two-dimensional materials with the aim of simultaneously enhancing NH<sub>3</sub> yield and Faradaic efficiency for electrocatalytic nitrogen reduction.