Drinking Water Purification by Electrosynthesis of Hydrogen Peroxide in a Power‐Producing PEM Fuel Cell

Abstract

The industrial anthraquinone auto-oxidation process produces most of the world's supply of hydrogen peroxide. For applications that require small amounts of H2 O2 or have economically difficult transportation means, an alternate, on-site H2 O2 production method is needed. Advanced drinking water purification technologies use neutral-pH H2 O2 in combination with UV treatment to reach the desired water purity targets. To produce neutral H2 O2 on-site and on-demand for drinking water purification, the electroreduction of oxygen at the cathode of a proton exchange membrane (PEM) fuel cell operated in either electrolysis (power consuming) or fuel cell (power generating) mode could be a possible solution. The work presented here focuses on the H2 /O2 fuel cell mode to produce H2 O2 . The fuel cell reactor is operated with a continuous flow of carrier water through the cathode to remove the product H2 O2 . The impact of the cobalt-carbon composite cathode catalyst loading, Teflon content in the cathode gas diffusion layer, and cathode carrier water flowrate on the production of H2 O2 are examined. H2 O2 production rates of up to 200 μmol h(-1) cmgeometric (-2) are achieved using a continuous flow of carrier water operating at 30 % current efficiency. Operation times of more than 24 h have shown consistent H2 O2 and power production, with no degradation of the cobalt catalyst.

Tailoring the Electrochemical Production of H2O2: Strategies for the Rational Design of High‐Performance Electrocatalysts

“…The geometric arrangement of atoms on the catalyst surface has also been observed to be a large determinant of the O 2 reduction selectivity to either H 2 O or H 2 O 2 15,16b. Choi et al observed that O 2 adsorption on pristine Pt/C catalysts followed a thermodynamically favored side‐on adsorption configuration ( Figure ) 16b. In this configuration, the O‐O bond of O 2 molecule is weakened by the adjacent sites, inducing O 2 dissociation to form H 2 O following the four‐electron pathway.…”

“…Mechanism of ORR on a) pristine Pt/C promoting side‐on configuration to induce four‐electron pathway via 1) dissociative, ) associative, and ) nondissociative mechanisms versus b) carbon‐coated Pt creating both side‐on and end‐on configurations to induce two‐ and four‐electron pathways. Reproduced with permission 16b. Copyright 2014, American Chemical Society.…”

“…Although the approach of obstructing adjacent sites with inert species to force the formation of single sites resulted in a higher selectivity for H 2 O 2 formation, the corresponding catalytic activity was limited due to the high proportion of occluded active sites 16b. Alternately, site isolation can also be achieved by decreasing the catalyst loading on supports.…”

“…Therefore, the optimal catalyst should minimize the kinetic barriers for O 2 adsorption and *OOH desorption to ensure high reduction activity, while maximizing the kinetic barriers for *OOH reduction/dissociation to *O and *OH for selectivity toward H 2 O 2 . Similarly, the stability of H 2 O 2 may also be compromised by extended residence time and high electrolyte pH, inducing further reduction and disproportionation of H 2 O 2 to H 2 O. In this sense, the selectivity toward H 2 O 2 can be enhanced via careful catalyst design, while the stability of the product solution can be enhanced via reactor and system design.…”

Risk of Getting Nosocomial Water-Borne Infections from the Main Water Systems in Hospitals

“…However, it may not be preferred in old water systems because of the risk for leakage when the biofilm is removed [51]. Electrolytic treatment of water can also remove biofilm and is commonly used in many formats [52,53]. Decontamination of water with ultra violet light or large filters has been used on the incoming water supply to the building [54].…”