Spatially Segregated Pt/Co Dual Single-Atoms on Janus MXene Synergistically Boost Electrocatalytic Overall Water Splitting.

Zhang, Jian; Zhang, Luxin; Zhao, Boya; Guan, Yuze; Li, Yonghua; Chen, Wei; Li, Xing'ao; Zhu, Xinbao et al. · ACS Nano · 2026

basic_science · Level V

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Abstract

Spatial precision in the organization of active sites enables high-performance bifunctional electrocatalysts for overall water splitting. Herein, a stepwise defect-induced in situ intercalation strategy is developed to anchor Pt and Co single atoms on the two opposing facets of Ti<sub>3</sub>C<sub>2</sub>T<sub><i>y</i></sub> MXene, respectively, realizing separate-sided functionalization of monolayer Ti<sub>3</sub>C<sub>2</sub>T<sub><i>y</i></sub> with Pt/Co dual single atoms (Pt/Co DSA-Ti<sub>3-<i>x</i></sub>C<sub>2</sub>T<sub><i>y</i></sub>). The fabricated Janus Pt/Co DSA-Ti<sub>3-<i>x</i></sub>C<sub>2</sub>T<sub><i>y</i></sub> exhibits superior bifunctional electrocatalytic performance in an alkaline electrolyte, originating from the distinct roles of the two facets: Pt SAs on one side drive the HER (20.0 mV @ 10 mA cm<sup>-2</sup>), whereas Co single atoms on the other side deliver the impressive OER performance (195.0 mV @ 10 mA cm<sup>-2</sup>). The Janus electrocatalyst exhibits an ultralow overall water splitting overpotential of only 1.45 V to achieve 10 mA cm<sup>-2</sup>. Additionally, as bifunctional electrodes in AEMWE, Pt/Co DSA-Ti<sub>3-<i>x</i></sub>C<sub>2</sub>T<sub><i>y</i></sub> demonstrates a low voltage of 1.81 V at 1.0 A cm<sup>-2</sup> with a 200 h stability. In situ/operando spectroscopy and DFT calculations unveil that Pt/Co DSAs synergistically induce charge redistribution on the MXene surface, thus optimizing the active-site electronic states and intermediate adsorption to lower the reaction energy barrier. Our strategy serves as a pathway for atomically precise control of MXene-supported single-atom sites toward selective electrocatalysis.