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Composition-Dependent Electrocatalytic Activity of Zn-Doped Ni5P4 Nanocrystals for the Hydrogen Evolution Reaction
被引:5
作者:
Graves, Lisa S. S.
[1
]
Sarkar, Rajib
[1
]
Lao, Ka Un
[1
]
Arachchige, Indika U. U.
[1
]
机构:
[1] Virginia Commonwealth Univ, Dept Chem, Richmond, VA 23284 USA
基金:
美国国家科学基金会;
关键词:
NICKEL PHOSPHIDE;
SIZE;
CATALYSTS;
NI2P;
PHOSPHORUS;
MORPHOLOGY;
NANOSHEETS;
SURFACE;
MO;
D O I:
10.1021/acs.chemmater.3c01229
中图分类号:
O64 [物理化学(理论化学)、化学物理学];
学科分类号:
070304 ;
081704 ;
摘要:
Electrocatalyticwater splitting presents an exciting opportunityto produce environmentally benign hydrogen fuel to power human activities.Earth-abundant Ni5P4 has emerged as an efficientcatalyst for the hydrogen evolution reaction (HER), and its activitycan be enhanced by admixing synergistic metals to modify the surfaceaffinity and consequently the kinetics of HER. Computational studiessuggest that the HER activity of Ni5P4 can beimproved by Zn doping, causing a chemical pressure-like effect onNi(3) hollow sites. Herein, we report a facile colloidalroute to produce Ni5-x Zn x P4 nanocrystals (NCs) with control overstructure, morphology, and composition and investigate their composition-dependentHER activity in alkaline solutions. Ni5-x Zn x P4 NCs retain thehexagonal structure and solid spherical morphology of binary Ni5P4 NCs, with a notable size increase from 9.2-28.5nm for x = 0.00-1.27 compositions. Elementalmaps affirm the homogeneous ternary alloy formation with no evidenceof Zn segregation. Surface analysis of Ni5-x Zn x P4 NCs indicatessignificant modulation of the surface polarization upon Zn incorporation,resulting in a decrease in Ni & delta;+ and an increase inP(& delta;-) charges. Although all compositions followeda Volmer-Heyrovsky HER mechanism, the modulated surface polarizationenhances the reaction kinetics, producing lower Tafel slopes for Ni5-x Zn x P4 NCs (82.5-101.9 mV/dec for x = 0.10-0.84)compared to binary Ni5P4 NCs (109.9 mV/dec).Ni5-x Zn x P4 NCs showed higher HER activity with overpotentialsof 131.6-193.8 mV for x = 0.02-0.84in comparison to Ni5P4 NCs (218.1 mV) at a currentdensity of -10 mA/cm(2). Alloying with Zn increasesthe material's stability with only a & SIM;10% increase inoverpotential for Ni4.49Zn0.51P4 NCsat -50 mA/cm(2), whereas a & SIM;33% increase wasobserved for Ni5P4 NCs. At current densitiesabove -40 mA/cm(2), bimetallic NCs with x = 0.10, 0.29, and 0.51 compositions outperformed the benchmark Pt/Ccatalyst, suggesting that hexagonal alloyed Ni5-x Zn x P4 NCsare excellent candidates for practical applications that necessitatelower HER overpotentials at higher current densities.
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页码:6966 / 6978
页数:13
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