Atomically Dispersed Ni Species Confined in Low-Valent Manganese Oxide for Efficient Photothermal Reverse Water–Gas Shift Reaction

Abstract

Photothermal catalysis under mild conditions offers a promising approach for converting CO2 into value-added chemicals. Herein, we propose a strategy to achieve atomic dispersion of Ni on a low-valence metal oxide (MnO), enabling the Ni species to maintain a stable atomically dispersed state under reducing atmospheres (NiAD/MnO). In comparison, the Ni atoms anchored on high-valence MnO2 go through high-temperature reduction aggregation and sintering due to the crystal phase transformation of the support (NiNP/MnO). In the photothermal reverse water–gas shift (RWGS) reaction, NiAD/MnO achieved a CO production rate of 9.9 mmol g–1 h–1 with 99.9% CO selectivity (410 °C), far exceeding the performance of NiNP/MnO. Transient experiments and in situ spectroscopic characterization revealed that the photothermal RWGS reaction proceeds via a redox mechanism mediated by axial oxygen atoms coordinated with Ni. Theoretical calculations further demonstrated that light irradiation boosted the CO2 hydrogenation via effectively reducing the energy barrier for *CO desorption on NiAD/MnO.