On the electrocatalytic symbiotic synergism between Pt, Ni and Al in plasma vapour deposited Pt<inf>x</inf>Ni<inf>y</inf>Al<inf>z</inf> thin metal films for water electrolysis

Abstract

This work highlights the fact that the activity of an already active metal/surface, i.e. Ni, can be increased even further by combining it with metals/surfaces that exhibit low activity, i.e. Pt and Al, when used on their own. Combinatorial screening was conducted on plasma vapour deposited PtxNiyAlz thin-film ratios for the oxygen evolution reaction in alkaline medium. All co-deposited thin films were simultaneously evaluated employing a multichannel potentiostat with Pt9Ni56Al35 exhibiting the highest current at 1.39 V (SHE). Subsequent deposition on a glassy carbon insert followed by electrochemical characterization revealed that Pt9Ni56Al35 performed better than its constituent components in that it exhibited an overpotential of 487 mV at 10 mA cm−2 compared to 590 mV, 941 mV, and 1379 mV for the overpotentials of vapour deposited Ni, Pt and Al respectively. Subsequent evaluation of co-deposited Pt9Ni56Al35, as an electrocatalyst on a nickel woven mesh anode inside a membraneless divergent electrode-flow-through (DEFT™) alkaline electrolyser, resulted in a current density of 1198 mA cm−2 at a cell potential of 2 VDC. This represents the highest current density to date for a membraneless alkaline electrolyser.