Modulating active sites via Mn-doping in NiCo LDH for energy-saving paired electrosynthesis of H2O2 and formate

Electrochemical H 2 O 2 synthesis via the two-electron oxygen reduction reaction (2e – ORR) offers a green alternative to the energy-intensive anthraquinone process, but its practical viability is hindered by the sluggish and low-value oxygen evolution reaction (OER) at the anode. Here, we present an energy-saving paired electrolysis strategy that replaces anodic OER with methanol oxidation reaction (MOR) using a ternary Mn-doped NiCo layered double hydroxide (Ni 0.50 Co 0.30 Mn 0.20 LDH) catalyst in situ grown on nickel foam (NF) by a one-step hydrothermal method. The optimized catalyst achieves a low MOR potential of 1.32 V RHE at 10 mA cm –2 and a formate Faradaic efficiency of 92.9%, outperforming its undoped counterpart (Ni 0.61 Co 0.39 LDH, 1.37 V RHE and 83.3%). In-situ Raman spectroscopy and density functional theory calculations reveal that Mn doping lowers the energy barrier for the Ni 2+ /Ni 3+ redox transition, facilitating the generation of catalytically active Ni 3+ species. When coupled with graphitized hydroxyl-functionalized multi-walled carbon nanotubes coated on carbon paper (CNTs@CP) as the 2e – ORR cathode in a two-electrode electrolyzer, at the operation condition of 50 mA cm –2 , the 2e – ORR||MOR system delivers a cell voltage reduction of 254 mV, enabling a 10.3% decrease in energy consumption for H 2 O 2 production, compared with the conventional 2e – ORR||OER system. Moreover, the simultaneous generation of value-added formate at the anode yields a 97.9% increase in net economic benefit. This work establishes a generalizable paired electrolysis paradigm for the decentralized, energy-efficient, and economically viable co-production of H 2 O 2 and high-value chemicals.