Polyoxometalate-Anchored Ni-MOF for High-Efficiency, Selective H₂O₂ Electrosynthesis

Abstract

The 2-electron oxygen reduction reaction presents a promising alternative to the energy-intensive anthraquinone process for H2O2 production, but developing high-selectivity catalysts remains challenging. This study demonstrated a highly efficient non-precious metal electrocatalyst (FeMo6/Ni MOF-8) by combining FeMo6 with Ni MOF containing unsaturated coordinated metal sites at room temperature. The unsaturated metal sites enhanced both intrinsic catalytic activity and polyoxometalate (POM) anchoring, while the interfacial electron transfer from MOF to POM effectively regulated the electronic structure of POM/MOF, synergistically enhancing oxygen reduction activity. The catalyst showed excellent electrocatalytic activity under alkaline conditions, with an initial potential of 0.72 V (vs RHE), H2O2 selectivity of 94.3%, production rate of 169.81 mmol g cat-1 h-1, and stable operation over 50000 seconds at 0.2 V (vs RHE). Density functional theory (DFT) calculations revealed that the improvement of the MOF framework via POM doping shortened the Ni–Ni distance, thereby strengthening the interaction with O₂ and stabilizing the O-O bond during the reduction process. This electronic and structural modification effectively improved the intrinsic oxygen reduction reaction (ORR) activity of the POM/MOF composite. This study provided a new design principles of catalysts for the electrochemical synthesis of H2O2.