Morphological Modulation of Co2C by Surface-Adsorbed Species for Highly Effective Low-Temperature CO2 Reduction

Modulating the morphologies of transition metal carbides (TMCs) in situ in gas-solid reactions to improve catalytic performance remains a major challenge. Herein, we present a mechanism for manipulating prismatic and spherical Co2C by altering the surface energy and crystal growth rate by influencing the generation and amount of carboxylate species on hollow cubic Co3O4 (without Mn). Co2C nanoprisms delivered an excellent activity in reverse water gas shift (RWGS) at 270 degrees C, where CO2 conversion was close to thermodynamic limitations at a space velocity of 60 000 mL g(cat )h(-1). Furthermore, it showed a bifunctional effect that bridged RWGS and Fischer-Tropsch synthesis reactions, allowing for the direct synthesis of olefins and alcohols (C2+ OH/ROH fraction of 98.4%, 4.3 mmol g(-1)h(-1)) by adjusting reaction conditions. The catalytic performance of Co2C nanoprisms was linked to (020) and (101) surfaces with high activity as well as double reaction pathways (redox and formate routes) through reaction mechanism and kinetics studies. This investigation provides a method for designing and modulating morphologies of TMCs and exhibits great potential for bridging RWGS and sequent cascade reactions.

Automated summary

This study presents a mechanism for modulating the morphologies of transition metal carbides (TMCs) in gas-solid reactions to improve their catalytic performance. By influencing the generation and amount of carboxylate species on hollow cubic Co3O4, the researchers were able to manipulate the prismatic and spherical Co2C nanocrystals. The Co2C nanoprisms showed excellent activity in reverse water gas shift (RWGS) and bridged RWGS and Fischer-Tropsch synthesis reactions, allowing for the direct synthesis of olefins and alcohols.