Hydrogen Evolution Reaction on Pt/RuO2-TiO2 Electrocatalyst in Alkaline Media

Abstract

Hydrogen is poised to be a key energy carrier in a sustainable energy economy (1). Among the different approaches to produce hydrogen, water electrolysis has received special attention due to its unique advantages including reactant availability, safety, stable output and product purity (2). Alkaline water electrolysis offers additional advantages, including the possibility of using stainless steel flow fields and endplates (with the subsequent reduction in costs) and the possibility of using cheaper non-platinum-group-metal electrocatalysts for the oxygen evolution reaction. However, the slow kinetics for the hydrogen evolution reaction (HER) in alkaline media is currently a key drawback. In this work we evaluated a mixed-metal-oxide composed of titanium dioxide and ruthenium dioxide as a support for Pt and measured the catalytic activity of this supported electrocatalys for the HER. The mixed-metal-oxide (TiO2-RuO2, RTO) was synthesized using a wet chemical synthesis procedure, and the Pt/RTO was synthesized by reduction of Pt precursor onto the support using an impregnation-reduction method. These materials were characterized by XRD, TEM and BET. The activity of Pt/RTO towards HER the was compared with a benchmark Pt/C catalyst (46%Pt; Tanaka, K. K.). Rotating disk electrode (RDE) measurements showed Pt/RTO outperforming (under all the conditions) the benchmark catalyst (Pt/C). The specific exchange current density for Pt/RTO was 2.51mA/cm2 Pt (295 K, 1600rpm, H2-saturated 0.1M KOH), more than five times that of Pt/C. The catalysts were also evaluated in a solid-state water electrolyzer operated with ultrapure water at 50°C, wherein MEAs were prepared with IrO2 as a common anode electrocatalyst. The MEAs fabricated with Pt/RTO as the cathode catalyst outperformed the benchmark catalyst by 0.1-0.2 V across relevant current densities (see Figure 1). 1. M. S. Dresselhaus and I. L. Thomas, Nature, 414, 332 (2001). 2. H. Yin, S. Zhao, K. Zhao, A. Muqsit, H. Tang, L. Chang, H. Zhao, Y. Gao and Z. Tang, Nat Commun, 6, 6430 (2015). Figure 1