Coupling Enteromorpha prolifera-derived N-doped biochar with Cu-Mo2C clusters for selective CO2 hydrogenation to CO

Abstract

CO₂ conversion to CO via the reverse water-gas shift (RWGS) reaction is limited by a low CO₂ conversion rate and CO selectivity. Herein, an efficient RWGS catalyst is constructed through Enteromorpha prolifera–derived N-rich mesoporous biochar (EPBC) supported atomic-level Cu-Mo₂C clusters (Cu-Mo₂C/EPBC). Unlike traditional activated carbon (AC) supported Cu-Mo₂C particles (Cu-Mo₂C/AC), the Cu-Mo₂C/EPBC not only presents the better graphitization degree and larger specific surface area, but also uniformly and firmly anchors atomic-level Cu-Mo₂C clusters due to the existence of pyridine nitrogen. Furthermore, the pyridine N of Cu-Mo₂C/EPBC strengthens an unblocked electron transfer between Mo₂C and Cu clusters, as verified by X-ray absorption spectroscopy. As a result, the synergistic effect between pyridinic N anchoring and the clusters interaction in Cu-Mo₂C/EPBC facilitates an improved CO selectivity of 99.95% at 500 ​°C compared with traditional Cu-Mo₂C/AC (99.60%), as well as about 3-fold CO₂ conversion rate. Density functional theory calculations confirm that pyridine N-modified carbon activates the local electronic redistribution at Cu-Mo₂C clusters, which contributes to the decreased energy barrier of the transition state of CO∗+O∗+2H∗, thereby triggering the transformation of rate-limited step during the redox pathway. This biomass-derived strategy opens perspective on producing sustainable fuels and building blocks through the RWGS reaction.