Competitive Desorption Enables Room-Temperature CO and H2O Co-release in Reverse Water–Gas Shift over Noble-Metal-Free Cluster Co3O2–

Abstract

Reverse water–gas shift (RWGS, CO2 + H2 → CO + H2O) represents a pivotal strategy for CO2 hydrogenation. Although noble-metal (NM) catalysts are efficient, their scarcity necessitates the development of non-noble alternatives, while the mechanisms of elementary steps involved in RWGS over non-NM systems remains elusive. Herein, by combining mass spectrometry and quantum-chemical calculations, we demonstrate the room-temperature cogeneration of CO and H2O via competitive desorption on the reaction of cobalt oxide cluster Co3O2– with H2 followed by CO2. The comparable intensities of signals of Co3O3H2– (from CO desorption) and Co3O2CO– (from H2O desorption) in mass spectra provide solid experimental evidence for this phenomenon. Note that only one RWGS product (CO or H2O) typically desorbs at a given temperature owing to thermodynamic constraints, and rhodium is widely considered essential for driving RWGS. The synergistic and comparable electron-withdrawing abilities of both adsorbates, arising from orbital delocalization across Co and two species on Co3O2–, are emphasized to promote the desorption of either CO or H2O.