A Three-dimensional Floating Air Cathode with Dual Oxygen Supplies for Energy-efficient Production of Hydrogen Peroxide

Abstract

The in situ and cleaner electrochemical production of hydrogen peroxide (H2O2) through two-electron oxygen reduction reaction has drawn increasing attentions in environmental applications as an alterantive to traditional anthraquinone process. Air cathodes avoid the need of aeration, but face the challenges of declined performance during scale-up due to non-uniform water infiltration or even water leakage, which is resulted from changing water pressures and immature cathode fabrication at a large scale. To address these challenges, a three-dimensional (3-D) floating air cathode (FAC) was built around the commercial sponge, by coating with carbon black/poly(tetrafluoroethylene) using a simple dipping-drying method. The FAC floated on the water-air interface without extensive water-proof measures, and could utilize oxygen both from passive diffusion and anodic oxygen evolution to produce H2O2. The FAC with six times of dipping treatment produced a maximum H2O2 concentration of 177.9 ± 26.1 mg L−1 at 90 min, with low energy consumption of 7.1 ± 0.003 Wh g−1 and stable performance during 10 cycles of operation. Our results showed that this 3-D FAC is a promising approach for in situ H2O2 production for both environmental remediation and industrial applications.

Modular Hydrogen Peroxide Electrosynthesis Cell with Anthraquinone-Modified Polyaniline Electrocatalyst

“…The AQ-PANI's capacity to generate H 2 O 2 was likely not fully realized by limited O 2 transport in a batch mode and in an immersed electrode setup. 13,42,43 We fabricated a flow cell equipped with a gas diffusion cathode loaded with AQ-PANI(NS-CNT) as a working prototype (Figure 4a). 8 The gas diffusion electrode has been verified in our previous study to mitigate the O 2 transport limitation.…”

Superhydrophobic Air-Breathing Cathode for Efficient Hydrogen Peroxide Generation through Two-Electron Pathway Oxygen Reduction Reaction

“…A typical air-cathode, composed of a hydrophobic gas-diffusion layer (GDL) facing the air and a submerged catalyst layer (CL) facing to the electrolyte, which maintains an O 2 diffusion path from air and then enables oxygen reduction on the cathodes . In previous research, different air-cathodes were developed for two-electron ORR to generate H 2 O 2 . , Our group reported a heteroatom-free carbon black/graphite (CB&G) hybrid air-breathing cathode using PTFE as binder, which was proved efficient for H 2 O 2 production. , It is well-known that an ideal balance of hydrophilicity and hydrophobicity can result in a steady three-phase interface (TPIs) among the electrolyte solution, O 2 and catalytic sites in the CL for the sustainable electro-generation of H 2 O 2 . , The solid phase offers electron and catalyst, the gas phase is responsible for gas diffusion, and the liquid phase supplies proton as well as transfer products. However, an ideal balance of hydrophilicity and hydrophobicity has hardly been investigated for air cathodes.…”

“…22 In previous research, different air-cathodes were developed for two-electron ORR to generate H 2 O 2 . 23,24 Our group reported a heteroatom-free carbon black/graphite (CB&G) hybrid air-breathing cathode using PTFE as binder, which was proved efficient for H 2 O 2 production. 25,26 It is wellknown that an ideal balance of hydrophilicity and hydrophobicity can result in a steady three-phase interface (TPIs) among the electrolyte solution, O 2 and catalytic sites in the CL for the sustainable electro-generation of H 2 O 2 .…”

Synergetic Photocatalytic Pure Water Splitting and Self-Supplied Oxygen Activation by 2-D WO3/TiO2 Heterostructures

“…As a typical multiphase process, the efficiency of the photocatalytic reaction is highly dependent on the mass transfer of reactants over heterogeneous catalysts. Therefore, outcomes of photocatalytic ROS formation is practically restricted by the inadequate oxygen supply because of the low solubility (8.1–8.5 ppm at 25 °C) and small diffusion coefficient (1.96 to 2.56 × 10 –9 m 2 s –1 at 25 °C) of oxygen in water . To solve this problem, active aeration is commonly used to afford external O 2 for reoxygenation.…”

“…Therefore, outcomes of photocatalytic ROS formation is practically restricted by the inadequate oxygen supply because of the low solubility (8.1−8.5 ppm at 25 °C) and small diffusion coefficient (1.96 to 2.56 × 10 −9 m 2 s −1 at 25 °C) of oxygen in water. 5 To solve this problem, active aeration is commonly used to afford external O 2 for reoxygenation. However, the power consumption in the aeration reactor undoubtedly increases the operating costs.…”