Overpotential analysis of alkaline and acidic alcohol electrolysers and optimized membrane-electrode assemblies

Abstract

Alcohol electrolysis using polymeric membrane electrolytes is a promising route for storing excess renewable energy in hydrogen, alternative to the thermodynamically limited water electrolysis. By properly choosing the ionic agent (i.e. H + or OH-) and the catalyst support, and by tuning the catalyst structure, we developed membrane-electrode-assemblies which are suitable for cost-effective and efficient alcohol electrolysis. Novel porous electrodes were prepared by Atomic Layer Deposition (ALD) of Pt on a TiO2-Ti web of microfibers and were interfaced to polymeric membranes with either H + or OHconductivity. Our results suggest that alcohol electrolysis is more efficient using OHconducting membranes under appropriate operation conditions (high pH in anolyte solution). ALD enables better catalyst utilization while it appears that the TiO2-Ti substrate is an ideal alternative to the conventional carbon-based diffusion layers, due to its open structure. Overall, by using our developmental anodes instead of commercial porous electrodes, the performance of the alcohol electrolyser (normalized per mass of Pt) can be increased up to ∼30 times.

Graphene-like materials as an alternative to carbon Vulcan support for the electrochemical reforming of ethanol: Towards a complete optimization of the anodic catalyst

“…The main advantage of polymeric membrane cells is the ability to work at mild temperature conditions, unlike solid oxide electrolysis cells [6]. Additionally, proton exchange membranes (PEM) present a higher electrical conductivity (i.e., lower ohmic losses) compared to anion exchange membranes (AEM) [7]. The main advantages of ethanol are non-toxicity, high volumetric energy density, easy storage and handling, and the production of highly pure and clean hydrogen at mild reaction conditions, in contrast to natural gas steam reforming [8][9][10].…”

Methanol Oxidation at Platinum Coated Black Titania Nanotubes and Titanium Felt Electrodes

“…There are various methods for Pt deposition on titanium/titania substrates and these include chemical/hydrothermal/photochemical methods [ 33 , 34 , 35 , 36 ] (usually employed in the case of nanoparticle supports) and atomic layer deposition, ALD [ 42 , 47 , 51 ] as well as electrodeposition methods [ 37 , 38 , 39 , 40 , 41 , 43 , 44 , 45 , 46 , 48 ] (preferred for Ti and TNT substrates). An alternative method for deposition on Ti and TNT supports is that of spontaneous galvanic deposition of Pt from Pt(IV) complex solutions onto freshly etched/reduced Ti and TNTs.…”

Over-faradaic hydrogen production in methanol electrolysis cells

“…In order to overcome this issue, in the last years, alcohols electrolysis has gained growing attention for efficient production of hydrogen [6][7][8][9][10]. The thermodynamics for the electro-oxidation of alcohols is significantly favoured compared to that for water electrolysis (1-2 orders of magnitude, depending on the alcohol: 106 mV for 2-propanol, 84 mV for ethanol and 16 mV for methanol [11]). Therefore, in theory, this technology would allow drastically enhancing the production of hydrogen at lower electrical 4 potentials.…”