Aleksey Valerievich Nikiforov

Advanced Construction Materials for High Temperature Steam PEM Electrolysers

One of the potential advantages of PEM cells over more abundant alkaline electrolyzers is that they were shown to be reversible [21, 31, 69]. The type of an electrochemical cell working both as a fuel cell and a water electrolyzer is called a unitized regenerative fuel cells (URFC) [13, 38, 67, 70]. These devices produce hydrogen fromwater in the electrolysis mode, while electricity can be inversely produced in the fuel cell mode. This mode of working is beneficial when the lack of electricity changes with the excess energy available (periods of low consumption) [61].

Electrochemical Studies of Corrosion in Liquid Electrolytes for Energy Conversion Applications at Elevated Temperatures

Stainless steels (AISI 316, 321 and 347), high-nickel alloys (Hasteloy®C-276 and Inconel®625), tantalum, nickel, titanium, tungsten, molybdenum, niobium, platinum, and gold were tested for corrosion resistance in molten KH2PO4 (or KH2PO4-K2H2P2O7) as a promising electrolyte for the intermediate-temperature (200–400°C) water electrolysis. Pt, Ta, Nb, Ti, Inconel®625, and Ni demonstrated high corrosion resist‐ ance. Au and the rest of the tested materials were not corrosion resistant. It means that Ni, Ti and Inconel®625 may be used as relatively cheap construction materials for the intermediate-temperature water electrolyzer.

Development of Refractory Ceramics for the Oxygen Evolution Reaction (OER) Electrocatalyst Support for Water Electrolysis at Elevated Temperatures

Commercial TaC and Si3N4 powders were tested as possible electrocatalyst support materials for the Oxygen Evolution Reaction (OER) for PEM water electrolysers, operating at elevated temperatures. TaC and Si3N4 were characterised by thermogravimmetric and differential thermal analysis for their thermal stability. The Adams fusion method was implemented to deposit IrO2 on the support surfaces. A series of electrocatalysts was prepared with a composition of (IrO2)x(TaC/ Si3N4)1-x,where x represents the mass fraction of IrO2 and was equal to 0.1 (only for TaC), 0.3, 0.5, 0.7, 0.9 and 1. The thin-film method was used for electrochemical analysis of the prepared electrocatalysts. SEMEDX, BET and powder conductivity measurements were used as complementary techniques to complete characterisation of the electrocatalysts. Additionally, they were compared in their properties with previously reported data for a SiC-Si support. The stability of the electrocatalysts was assessed by estimation of reversibility of the anodic/cathodic processes.