Atomic Pt-Clusters Decoration Triggers a High-Rate Performance on Ni@Pd Bimetallic Nanocatalyst for Hydrogen Evolution Reaction in Both Alkaline and Acidic Medium

Dinesh Bhalothia,Sheng-Po Wang,Kuan-Wen Wang,Po-Chun Chen,Che Yan,Shuan Lin

doi:10.3390/app10155155

Abstract

The development of inexpensive and highly robust nanocatalysts (NCs) to boost electrochemical hydrogen evolution reaction (HER) strengthens the implementation of several emerging sustainable-energy technologies. Herein, we proposed a novel nano-architecture consisting of a hierarchical structured Ni@Pd nanocatalyst with Pt-clusters decoration on the surface (denoted by Ni@Pd-Pt) for HER application in acidic (0.5 M H2SO4) and alkaline (0.1 M KOH) mediums. The Ni@Pd-Pt NC is fabricated on a carbon black support via a “self-aligned” heterogeneous nucleation-crystal growth mechanism with 2 wt.% Pt-content. As-prepared Ni@Pd-Pt NC outperforms the standard Pt/C (30 wt.% Pt) catalyst in HER and delivers high-rate catalytic performance with an ultra-low overpotential (11.5 mV) at the cathodic current density of 10 mA∙cm−2 in alkaline medium, which is 161.5 mV and 14.5 mV less compared to Ni@Pd (173 mV) and standard Pt/C (26 mV) catalysts, respectively. Moreover, Ni@Pd-Pt NC achieves an exactly similar Tafel slope (42 mV∙dec−1) to standard Pt/C, which is 114 mV∙dec−1 lesser when compared to Ni@Pd NC. Besides, Ni@Pd-Pt NC exhibits an overpotential value of 37 mV at the current density of 10 mA cm−2 in acidic medium, which is competitive to standard Pt/C catalyst. By utilizing physical characterizations and electrochemical analysis, we demonstrated that such an aggressive HER activity is dominated by the increased selectivity during HER due to the reduced competition between intermediate products on the non-homogeneous NC surface. This phenomenon can be rationalized by electron localization owing to the electronegative difference (χPt > χPd > χNi) and strong lattice mismatch at the Ni@Pd heterogeneous binary interfaces. We believe that the obtained results will significantly provide a facile design strategy to develop next-generation heterogenous NCs for HER and related green-energy applications

Highlights

Hydrogen has been investigated as a potential candidate for the implementation of green-energy technologies, sustainable hydrogen production is the key prerequisite to this end [1,2]
X-ray photoelectron spectroscopy (XPS) of Ni@Pd-Pt and control samples was executed at beamlines BL-24A1 of the National Synchrotron Radiation Research Center (NSRRC), Taiwan
Ni@Pd (Figure 1a) nanoparticles exhibit a hierarchical structure, where long-range ordered atomic arrangements are observed on the surface due to capping of Pd-atoms over disorders Ni-atoms underneath

Summary

Introduction

Hydrogen has been investigated as a potential candidate for the implementation of green-energy technologies, sustainable hydrogen production is the key prerequisite to this end [1,2]. Our previous studies demonstrated that Pt-clusters decoration effectively shelters the catalyst surface from oxidation and creates intense active sites for HER facilitation [26,27,28,29,30,31] In such a unique structure, Pt-clusters are decorated on the Ni@Pd surface and at the heteroatomic interfaces of Ni-to-Pd; where the ligand effect (due to difference in electronegativity of adjacent atoms) and lattice strain (due to lattice mismatch) plays a key role at the heterogenous interfaces and relocate electrons to the NC surface, the formation of catalytic active sites takes place, which boosts the HER kinetics. This overpotential value is the same as a standard Pt/C catalyst

Experimental

Physical

Electrochemical Analysis

Results and Discussion

Conclusions