Metal-organic framework-derived hollow NiCo2O4 spinel arrays coupled with Pd-Ni bimetallic sites for efficient CO2 hydrogenation to formate

Abstract

CO₂ hydrogenation to formate is an effective strategy for promoting the sustainable carbon cycle. However, formate yields are significantly influenced by the amount of noble metal (e.g., Pd) used. Here, we present Pd-Ni synergistic catalysis on the hollow NiCo₂O₄ spinel arrays (Pd_xNi_y/NCO@CC) for enhanced formate production under mild conditions. The Pd-Ni dual-site structure effectively enhances electron accumulation on Pd via charge polarization and the synergistic interaction between Pd and Ni, leading to significantly improved formate yields with a reduced usage of noble metal catalyst. The optimized Pd₅Ni₅/NCO@CC catalyst achieved a remarkable formate yield of 282.5 mol_formate mol_Pd⁻¹ h⁻¹ at 333 K and demonstrated high stability. This strategy of synergistically enhancing catalytic activity via bimetallic sites highlights its advantages in other catalytic fields and practical applications.