Vacancy-Rich MXene-Immobilized Ni Single Atoms as a High-Performance Electrocatalyst for the Hydrazine Oxidation Reaction.

Zhou, Shiqi; Zhao, Yunxuan; Shi, Run; Wang, Yucheng; Ashok, Anumol; Héraly, Frédéric; Zhang, Tierui; Yuan, Jiayin · Adv Mater · 2022

basic_science · Level V

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Abstract

Single-atom catalysts (SACs), on account of their outstanding catalytic potential, are currently emerging as high-performance materials in the field of heterogeneous catalysis. Constructing a strong interaction between the single atom and its supporting matrix plays a pivotal role. Herein, Ti<sub>3</sub> C<sub>2</sub> T<sub>x</sub> -MXene-supported Ni SACs are reported by using a self-reduction strategy via the assistance of rich Ti vacancies on the Ti<sub>3</sub> C<sub>2</sub> T<sub>x</sub> MXene surface, which act as the trap and anchor sites for individual Ni atoms. The constructed Ni SACs supported by the Ti<sub>3</sub> C<sub>2</sub> T<sub>x</sub> MXene (Ni SACs/Ti<sub>3</sub> C<sub>2</sub> T<sub>x</sub> ) show an ultralow onset potential of -0.03 V (vs reversible hydrogen electrode (RHE)) and an exceptional operational stability toward the hydrazine oxidation reaction (HzOR). Density functional theory calculations suggest a strong coupling of the Ni single atoms and their surrounding C atoms, which optimizes the electronic density of states, increasing the adsorption energy and decreasing the reaction activation energy, thus boosting the electrochemical activity. The results presented here will encourage a wider pursuit of 2D-materials-supported SACs designed by a vacancy-trapping strategy.