A 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 a 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 MOFs to POMs effectively regulated the electronic structure of the POM/MOF composite, improving its electron transfer capacity and synergistically enhancing oxygen reduction activity. Density functional theory (DFT) calculations suggested that the improvement of the MOF via POM doping could shorten the Ni–Ni distance, thereby potentially 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. The catalyst showed excellent electrocatalytic activity under alkaline conditions, with an initial potential of 0.72 V (vs. RHE), a H₂O₂ selectivity of 94.3%, a production rate of 169.81 mmol g_cat⁻¹ h⁻¹, and stable operation for over 40 h at 0.5 V (vs. RHE). This study demonstrates a promising design strategy exemplified by the FeMo₆/Ni MOF system for high-efficiency electrochemical H₂O₂ synthesis.