Pressure-driven reconstruction of single-atom Ni-O-K interface for near-equilibrium CO2 hydrogenation

Pressure-driven reconstruction forms Ni-O-K single-atom interfaces. • Near-equilibrium CO 2 conversion (∼58%) with ∼100% CO selectivity. • Exceptional stability over 200 h without sintering or deactivation. • Ni-O-K sites lower E a and suppress methanation. • Carboxyl pathway dominates over formate route. Achieving simultaneous high activity, selectivity, and stability in single-atom catalysts (SACs) under high-temperature conditions remains a significant challenge, primarily due to the difficulty in precisely controlling the coordination environment of metal centers. Here, we demonstrate that alkali ion (e.g., K + ) modification of both Ni single atoms and their carbon nitride (CN) support enables exceptional performance in the reverse water-gas shift (RWGS) reaction. The resulting Ni@K-CN catalyst achieves near-equilibrium CO 2 conversion with nearly 100% CO selectivity across a broad temperature range (400–600 ℃), alongside remarkable long-term stability. This performance substantially surpasses that of the K-free analogue and ranks among the best-reported non-noble metal RWGS catalysts. Operando studies reveal that the catalyst undergoes a thermodynamically driven in-situ reconstruction under high pressure reaction conditions, forming atomically dispersed Ni-O-K interfacial sites within a restructured carbon nitride matrix. Density functional theory calculations reveal that these sites markedly lower the apparent activation energy ( E a = 41.5 vs. 131.4 kJ·mol −1 ), modulate the electronic structure of Ni and surface-adsorbate interactions, and thereby promote a low-energy-barrier carboxyl pathway while kinetically suppressing methanation. This work establishes a design strategy based on alkali-mediated dynamic reconstruction to create highly stable and selective SACs for demanding high-temperature catalytic processes. Download: Download high-res image (174KB) Download: Download full-size image