Surface engineering of GeO_2-TiO_2 composite electrode for enhanced electron transport characteristics and alkaline hydrogen evolution reaction

摘要

Herein, we report the fine tuning of electrocatalytic characteristics of CeO2-TiO2 composite by surface engineering to reduce overpotential and to improve exchange current density for enhanced alkaline hydrogen evolution reaction (HER). The enhanced electrocatalytic activity of the surface engineered CeO2-TiO2 composite through Ni and P decoration is attributed to the improved electron transport ability. The surface roughness characteristics and surface composition of electroactive species are tuned to generate high electronic conductivity on the surface engineered composite electrode surface. The developed hard electrode with leptokurtic surface (S-ku 3) exhibited a high average roughness value (Sa) of 3 mm due to incorporation of the mesoporous catalyst material into it. Tuning of a compact and continuous electrode surface with critical composition of elements Ni (52 at.%), P (20 at.%), Ce (9 at.%) and Ti (8 at.%) furnishes the high conductivity (contact potential difference = 0.83 V) to the electrode. The developed electrode with surface engineered CeO2-TiO2 catalyst exhibited a low overpotential of -111 mV (at a high current density of 250 mA cm(-2)) and high exchange current density (1.6 x 10(-1) mA cm(-2)) with low charge transfer resistance (615 Omega cm(2)). High electrocatalytic activity and stability of the surface engineered CeO2-TiO2 catalyst electrode during alkaline (32 w/v.% NaOH) HER ensure its promising performance and applicability for long term HER. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.