Room temperature synthesized layered CAU-17 MOFs for highly active and selective electrocatalytic CO2 reduction to formate

Modulating the morphology of metal-organic frameworks (MOFs) has been identified as an effective strategy for enhancing the electrocatalytic performance of CO2 reduction reactions (CO2RR). In this study, CAU-17 MOFs ([Bi(BTC)(H2O)]·2 H2O·MeOH) were prepared via a sonication-assisted method at room temperature, which is considered a simpler technique compared to the conventional hydrothermal method. Additionally, the morphology of CAU-17 MOFs was further regulated by incorporating a rare-earth metal (La), resulting in the observation of two distinct structures, i.e. CAU-17 hexagonal prism (CAU-17-HP) and CAU-17 layer (CAU-17-Layer). Compared to CAU-17-HP, CAU-17-Layer exhibits an excellent selectivity towards formate with the maximum Faradaic efficiency of 95.5% at − 1.1 VRHE in an H-cell. Subsequently, the limited catalytic activity of CAU-17-Layer was boosted by anchoring nano CeO2 onto its surfaces (CeO2 @CAU-17-Layer). The as-prepared composite catalyst demonstrated outstanding performance in the conversion of CO2 to formate, with a current density surpassing − 100 mA cm-2 at potentials more negative than − 1.0 VRHE and reaching − 200 mA cm-2 at − 1.5 VRHE in a flow cell. This study demonstrates the significant potential of morphology-engineered and rare-earth metals composited MOFs in facilitating highly efficient reduction of CO2. •Bismuth-based metal-organic frameworks (CAU-17 MOFs) were prepared via a sonication-assisted method at room temperature.•The morphology of CAU-17 MOFs was regulated by rare-earth metal (La).•Morphology engineering boosted the catalytic performance of CAU-17-MOFs.•When incorporating nano-CeO2 into CAU-17-Layer, the current density reached − 200 mA cm-2 at − 1.5 VRHE.