A low-valent alkali metal doping strategy for enhanced performance of high-entropy oxide catalysts in reverse water–gas shift reactions

Abstract

The reverse water–gas shift (RWGS) reaction is a key pathway for catalytic CO₂ valorization. Emerging high-entropy oxide (HEO) systems exhibit great catalytic potential; however, their activity remains suboptimal. In this work, we developed a Li-doping strategy to modify the (Mg₁Co₁Ni₁Cu₁Zn₁)O_α (J14) high-entropy oxide (HEO) catalyst, yielding enhanced RWGS catalytic performance. The Li-doped catalyst exhibited a CO generation rate of 210 μmol_CO g_cat⁻¹ s⁻¹ at 400 °C, 1.46 times higher than that of J14, with enhanced stability. Systematic characterization and experiments demonstrated that this approach effectively coordinates metal exsolution and dispersion while tailoring surface alkalinity, thereby enhancing both H₂ dissociation and CO₂ activation. Furthermore, a mechanistic shift from the redox pathway to the carbonate-associative pathway was observed. This low-valent alkali metal doping strategy offers a generalizable design principle for HEO catalysts.