Gaδ+-H active sites-driven reverse water gas shift reaction with high CO selectivity

The reverse water gas shift (RWGS) reaction has garnered significant attention for its ability to selectively convert CO 2 into CO. However, conventional transition metal catalysts often face challenges such as the generation of byproducts at low temperatures and sintering at high temperatures. In this study, a series of Ga/Al 2 O 3 catalysts with varying Ga loadings was prepared using the impregnation method. Notably, these catalysts exhibit nearly 100% CO selectivity across a broad temperature range of 300–700 °C, with stable catalytic activity maintained after 165 h of testing at 600 °C. Characterization reveals Ga species exist as highly dispersed Ga 2 O 3 on the Al 2 O 3 support. The formation of Ga δ+- H species occurs under an H 2 atmosphere, accompanied by the creation of oxygen vacancies. In situ DRIFTS spectroscopy confirms Ga δ+ -H as the key active site for RWGS, and this species undergoes reversible regeneration in a H 2 environment. This work first reveals the pivotal role of Ga δ+ -H in driving the highly selective RWGS reaction. By promoting CO 2 activation and the formation of key formate intermediates, it achieves nearly 100% CO selectivity. This discovery provides novel design insights and theoretical foundations for developing highly efficient CO₂ conversion catalysts.