期刊
CHEMICAL SCIENCE
卷 8, 期 4, 页码 2952-2958出版社
ROYAL SOC CHEMISTRY
DOI: 10.1039/c6sc05167g
关键词
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资金
- FCT Investigator grant [IF/01595/2014]
- Portuguese Foundation of Science & Technology (FCT) [IF/01595/2014/CP1247/CT0001]
- Marie Sklodowska-Curie Action COFUND programme (NanoTrainforGrowth) [600375]
- European Commission Horizon 2020 project CritCat [686053]
Electrochemical water splitting into hydrogen and oxygen is a promising technology for sustainable energy storage. The development of earth-abundant transition metal phosphides (TMPs) to catalyze the hydrogen evolution reaction (HER) and TMP-derived oxy-hydroxides to catalyze the oxygen evolution reaction (OER) has recently drawn considerable attention. However, most monolithically integrated metal phosphide electrodes are prepared by laborious multi-step methods and their operational stability at high current densities has been rarely studied. Herein, we report a novel vapor-solid synthesis of single-crystalline cobalt phosphide nanowires (CoP NWs) on a porous Co foam and demonstrate their use in overall water splitting. The CoP NWs grown on the entire surface of the porous Co foam ligaments have a large aspect ratio, and hence are able to provide a large catalytically accessible surface over a given geometrical area. Comprehensive investigation shows that under the OER conditions CoP NWs are progressively and conformally converted to CoOOH through electrochemical in situ oxidation/dephosphorization; the latter serving as an active species to catalyze the OER. The in situ oxidized electrode shows exceptional electrocatalytic performance for the OER in 1.0 M KOH, delivering 100 mA cm(-2) at an overpotential (eta) of merely 300 mV and a small Tafel slope of 78 mV dec(-1) as well as excellent stability at various current densities. Meanwhile, the CoP NW electrode exhibits superior catalytic activity for the HER in the same electrolyte, affording -100 mA cm(-2) at eta = 244 mV and showing outstanding stability. An alkaline electrolyzer composed of two symmetrical CoP NW electrodes can deliver 10 and 100 mA cm(-2) at low cell voltages of 1.56 and 1.78 V, respectively. The CoP NW electrolyzer demonstrates exceptional long-term stability for overall water splitting, capable of working at 20 and 100 mA cm(-2) for 1000 h without obvious degradation.
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