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.

Keywords

• Enteromorpha prolifera
• N-doped biochar
• Cu-Mo2C clusters
• Electronic interaction
• CO2 hydrogenation