Tuning electron back-donation to switch reaction pathway in CO2 hydrogenation

CO 2 hydrogenation over earth-abundant Ni catalysts is attractive for CO-based fuel synthesis, but Ni intrinsically favors methanation. Here we show that ordered Ni 3 Sn 2 intermetallics tune Ni–CO electron back-donation and switch CO 2 hydrogenation from CH 4 formation to the reverse water–gas shift reaction. Atomic-resolution microscopy and X-ray absorption spectroscopy reveal disruption of extended Ni–Ni ensembles by Sn, while spectroscopy and theoretical calculations show that Ni–Sn d - p hybridization downshifts the Ni 3 d band and weakens Ni→CO 2π* back-donation. The Ni 3 Sn 2 catalyst achieves CO 2 conversion approaching thermodynamic equilibrium with nearly 100% CO selectivity and remains stable for 300 h. In situ infrared spectroscopy, steady-state isotopic transient kinetic analysis and theoretical calculations indicate that H-assisted CO 2 activation, spectator-like formate species and facile CO desorption underpin the CO-selective pathway. Similar behavior over Ni–Ga and Ni–In catalysts suggests a general back-donation strategy for redirecting Ni-based CO 2 hydrogenation.