Highly efficient paired H2O2 production through 2e− water oxidation coupled with 2e− oxygen reduction

Electrochemical hydrogen peroxide (H2O2) synthesis from water and air via two-electron (2e−) water oxidation or oxygen reduction reactions could provide a sustainable route for on-site H2O2 production. Unfortunately, the electrochemical H2O-to-H2O2 process usually suffers from limited selectivity under high current density. Here, we present an atomic Ni-doped TiO2 electrocatalyst that enables H2O2 production through 2e− water oxidation with high Faradaic efficiency of 70% at ∼300 mA cm−2. Furthermore, when paired with the 2e− oxygen reduction reaction using the oxidized carbon nanotube cathode, as high as 146% Faradaic efficiency for H2O2 is achieved at 240 mA in a full flow cell device. Moreover, this device could be operated for modular H2O2 synthesis with a production rate of 109.12 μmol min−1 (i.e., 3.7 mg min−1). This work demonstrates the atomically controlled metal oxide electrocatalyst for harsh anodic H2O to H2O2 and the practical applicability for the on-site H2O2 production from earth-abundant resources. [Display omitted] •NixTi1-xO2-y catalyst with dispersive Ni atoms has been designed and synthesized•NixTi1-xO2-y can be used as an efficient electrocatalyst through WOR pathway•DFT demonstrate that the single Ni atoms could efficiently optimize the OH∗ adsorption•A full-cell device coupled anode with cathode is operated for paired H2O2 synthesis Electrochemical strategies offer an attractive route for on-site decentralized H2O2 production from water and air. The ideal one is paired H2O2 synthesis on both cathode via 2e− oxygen reduction and anode via 2e− water oxidation in a full-cell device. However, it usually suffers from the mismatch of H2O2 production rate and selectivity between anode and cathode due to lack of a highly efficient electrocatalyst for anodic H2O to H2O2 in neutral-to-weak alkaline media. Therefore, developing an anodic electrocatalyst featuring high activity and selectivity for the 2e− WOR process has become the focus of recent research works. In this work, we developed a highly efficient electrocatalyst for H2O2 synthesis on anode via 2e− WOR and then further coupled it with the cathodic 2e− ORR to concurrently produce H2O2 in a full-cell device. This full-cell device could be operated in weakly alkaline (pH ≈ 11) media under a high current of 240 mA to produce H2O2 with a Faradaic efficiency of 146%. A single atomic Ni-doped TiO2 electrocatalyst is designed and prepared to achieve H2O2 synthesis through 2e− water oxidation