Electrochemically Fabricated Surface-Mesostructured CuNi Bimetallic Catalysts for Hydrogen Production in Alkaline Media.

Jingyuan Bai,Zhou Yang,Longyi Fan,Dalong Yang,Yupu Hou,Konrad Eiler,Jin Zhang,Jordi Sort,Meilin Zhang,Renguo Guan,Eva Pellicer

doi:10.3390/nano12010118

Abstract

Ni-based bimetallic films with 20 at.% and 45 at.% Cu and mesostructured surfaces were prepared by electrodeposition from an aqueous solution containing micelles of P123 triblock copolymer serving as a structure-directing agent. The pH value of the electrolytic solution had a key effect on both the resulting Cu/Ni ratio and the surface topology. The catalytic activity of the CuNi films toward hydrogen evolution reaction was investigated by cyclic voltammetry (CV) in 1 M KOH electrolyte at room temperature. The Cu45Ni55 film showed the highest activity (even higher than that of a non-mesostructured pure Ni film), which was attributed to the Ni content at the utmost surface, as demonstrated by CV studies, as well as the presence of a highly corrugated surface.

Highlights

The electrochemical surface area (ECSA) and surface composition of the electrocatalysts were evaluated by electrochemical means. We demonstrate for this particular alloy that, a higher amount of Ni at the surface leads to better hydrogen evolution reaction (HER) performance, thereby confirming that the electrocatalytic activity is well correlated with ECSA and surface composition
In the plating solution, dissolved Cu and Ni ions are coordinated by water molecules forming metal–aqua complexes which adsorb onto the external ethylene oxide (EO) groups of the P123 micelles
The potential shifted toward more negative potential for the Cu45 Ni55 film during the first 45 min but it partially recovered and became stable from 5 h until the end of the experiment (E = −270 mV). These results suggest that the CuNi films experienced a decrease in the catalytic activity during the first hours, but no further decline of the activity was noticed after 5–6 h of continuous galvanostatic

Summary

Introduction

Bimetallic CuNi materials show significantly different properties compared to monometallic Ni [1,2]. The addition of Cu to Ni promotes the catalytic activity and selectivity of Ni toward a variety of reactions. The addition of a small amount of Cu to Ni/Al2 O3 increases the selectivity of 1,3-butadiene hydrogenation toward 1-butene [5]. An enhancement of the hydrogen evolution reaction (HER) of CuNi films with respect to their single counterparts has been reported [6]. The improvement observed in bimetallic systems tested at HER is due to a variety of reasons: preferential segregation of the most active metal to the surface, changes in the electronic properties, formation of large electrochemically active surface areas, and combinations thereof [7,8,9,10]

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