Water Splitting Catalysis Studied by using Real-Time Faradaic Efficiency Obtained through Coupled Electrolysis and Mass Spectrometry

An experimental setup and routine is presented for evaluating potential catalysts for water splitting by means of measuring the faradaic efficiency in real time through coupled potentiometry and mass spectrometry. The aim was to scale up an analytical cell unit towards the simulation of industrial conditions and generate results such as H-2 production versus power input at a certain potential or current density in addition to electrochemical parameters. Three types of electrodes were tested: A) planar metal electrodes; B) metal-foam-based electrodes; C) porous electrodes with carbon additive. The results verify that the experimental routine yields the desired accuracy, sensitivity, and a negligible accumulation of gaseous products in the cell; thus the faradaic efficiency is measured in real time. The metal-based electrodes of category A and B proved to be durable with low overpotentials and high gas output to power input, whereas three tested metal oxide electrodes in C revealed i) potential-dependent deviation in the faradaic efficiency, ii) phase decomposition, and iii) an optimum operational power range.