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Nickel phosphide polymorphs with an active (001) surface as excellent catalysts for water splitting
Since the emergence of hydrogen generation by water-splitting as a core renewable-energy technology, the development of related catalysts with high efficiency, long-term stability, and low cost has been vigorously pursued. We report the temperature-controlled synthesis of two nickel phosphide polymo...
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Published in: | CrystEngComm 2019, Vol.21 (7), p.1143-1149 |
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Main Authors: | , , , , , , , , |
Format: | Article |
Language: | English |
Subjects: | |
Citations: | Items that this one cites Items that cite this one |
Online Access: | Get full text |
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Summary: | Since the emergence of hydrogen generation by water-splitting as a core renewable-energy technology, the development of related catalysts with high efficiency, long-term stability, and low cost has been vigorously pursued. We report the temperature-controlled synthesis of two nickel phosphide polymorphs, Ni
2
P and Ni
5
P
4
, by phosphorization of Ni foil or foam using phosphine gas. The hexagonal phase Ni
2
P nanowires and Ni
5
P
4
nanosheets were grown on Ni substrates with vertical alignment, and uniformly exposed active (001) planes. The Ni
5
P
4
nanosheets possess significant stacking faults along the [0001] direction. Both Ni
2
P and Ni
5
P
4
exhibit excellent electrocatalytic activity toward the hydrogen evolution reaction (HER). Their overpotential for 10 mA cm
−2
was 0.126 and 0.114 V, and the Tafel slope was 42 and 34 mV dec
−1
in 0.5 M H
2
SO
4
electrolyte, respectively. A decrease in HER performance was observed for Ni
5
P
4
, but the change was negligible for Ni
2
P. Strain mapping using a precession-assisted nanobeam electron diffraction technique showed that only Ni
5
P
4
underwent degradation of basal (001) planes during HER, which explains the lower stability of catalytic activity. Furthermore, the Ni
2
P nanowires demonstrated excellent catalytic activity toward overall water splitting, which could be attributed to the stable surface as well as the highly conductive crystal structures.
We report the temperature-controlled synthesis of two nickel phosphide polymorphs, Ni
2
P and Ni
5
P
4
, by phosphorization of Ni foil or foams using phosphine gas, and their excellent catalytic activity toward hydrogen evolution reaction. |
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ISSN: | 1466-8033 1466-8033 |
DOI: | 10.1039/c8ce01884g |