CO driven tunable syngas synthesis via CO2 photoreduction using a novel NiCo bimetallic metal-organic frameworks

Abstract

Syngas has important industrial applications, and converting CO₂ to CO is critical for syngas production. Metal-organic frameworks (MOFs) have demonstrated significant potential in photocatalytic syngas conversion, although the impact of catalytic reactions on tunable H₂/CO ratios remains unclear. Herein, we present a novel bimetallic NiCo-MOF catalyst, Ni_0.4Co_0.6, exhibiting high catalytic activity in syngas conversion due to the CO product self-driven effect. Our investigation, integrating experimental data with density functional theory (DFT) analysis, uncovers a high photocurrent response and a low charge-transfer resistance. Furthermore, the introduction of cobalt into Ni-MOF caused an upshift of the d-band center, which facilitated the conversion efficiency of *COOH intermediates, which has been identified as the rate-determining step in CO₂ conversion, resulting in increased CO yield. Additionally, the concentration of undesorbed CO rises, while CO co-adsorption diminishes the catalyst's binding energy for *H, thereby enhancing H₂ generation. These combined effects contribute to a self-driven enhancement in the catalytic production of syngas. By adjusting the Ni/Co ratio, a tunable H₂/CO ratio (0.21-0.85) was achieved, with Ni_0.4Co_0.6 exhibiting optimal catalytic performance, yielding 17.6 mmol·g^-1·h^-1 gas products. This study provides a novel insight into the correlation between reaction products and catalyst design, offering a perspective on perspective on modulating syngas composition.

Keywords: CO(2) reduction; CO-driven; Metal organic frameworks; Photocatalytic; Syngas tuning.