Issue 15, 2016

Fast fabrication of self-supported porous nickel phosphide foam for efficient, durable oxygen evolution and overall water splitting

Abstract

Self-supported three-dimensional porous nickel phosphide (Ni–P) foam has been fabricated by exposing commercially available Ni foam in phosphorus vapor at an elevated temperature for a short period of time. The as-fabricated Ni–P foam consists of Ni2P skeletons covered with vertically aligned Ni5P4–NiP2 nanosheets. When used as a self-supported anode to catalyze the oxygen evolution reaction (OER), it exhibits exceptionally high catalytic current density (191.0 mA cm−2 at an overpotential of η = 0.35 V) and outstanding long-term stability and durability (affording 10 mA cm−2 at 1.45 V vs. RHE for 26 h without degradation). Scanning electron microscopy, transmission electron microscopy, and X-ray diffractometry analyses show that during the galvanostatic OER electrolysis the surface Ni–P nanosheets are transformed to nickel oxide/hydroxide (NiO/Ni(OH)x), forming a Ni–P/NiO(Ni(OH)x) heterojunction on ligament surfaces of the porous Ni–P foam which would enhance the OER performance. The synergistic effect between Ni–P and NiO/Ni(OH)x is also confirmed by control experiments with self-supported NiO and Ni(OH)2 nanosheet electrodes. An alkaline electrolyzer has been built using two identical self-supported porous Ni–P foams as the anode and cathode, respectively. The electrolyzer exhibits superior electrolysis efficiency of 90.2% at 10 mA cm−2, and can maintain sufficiently high efficiency of 72.2% even at 100 mA cm−2. Moreover, the electrolyzer is substantially durable when working at 10 and 20 mA cm−2, splitting water constantly up to 1000 h with only a minor variation in the cell's voltage. The self-supported porous Ni–P foam holds substantial promise for use as both cathode and anode in industrial alkaline water electrolyzers.

Graphical abstract: Fast fabrication of self-supported porous nickel phosphide foam for efficient, durable oxygen evolution and overall water splitting

Supplementary files

Article information

Article type
Paper
Submitted
16 Dec 2015
Accepted
16 Mar 2016
First published
16 Mar 2016

J. Mater. Chem. A, 2016,4, 5639-5646

Fast fabrication of self-supported porous nickel phosphide foam for efficient, durable oxygen evolution and overall water splitting

X. Wang, W. Li, D. Xiong and L. Liu, J. Mater. Chem. A, 2016, 4, 5639 DOI: 10.1039/C5TA10317G

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