The
development of hydrogen production by water splitting was greatly
limited by the slow kinetics of the oxygen evolution reaction (OER).
Here, we found that the performance and efficiency of the electrocatalyst
for OER can be improved by designing the defect structure of the nanocatalyst
and heteroatom doping. In this study, we have successfully prepared
defect-rich metal Fe-doped CoP nanosheets (noted as Fe–CoP
NSs) as an efficient electrocatalyst for OER through an etching-cooperative
strategy. The doping rate of the Fe element is about 0.18%. Surprisingly,
Fe–CoP NSs possess a smaller overpotential (312 mV) and Tafel
slope (56.1 mV dec–1) than commercial RuO2 (344 mV and 62.4 mV dec–1) to drive the current
density of 10 mA cm–2 in 1 M KOH. In addition, Fe–CoP
NSs have great stability and robustness, which was demonstrated by
20 h of chronoamperometry test and 2000 cyclic voltammetry cycles.
The reasons for the excellent catalytic performance and robustness
of Fe–CoP NSs may be ascribed to the facts that defect-rich
NSs can expose more active sites and the heteroatom doping adjusts
the electronic structure of the catalyst, thereby promoting the OER
performance.
Developing low-cost and effective electrocatalysts for the hydrogen evolution reaction (HER) to replace Pt-group metals is a continuous challenge. Recently, transition metal phosphides have received increasing attention owing to their high intrinsic activity in catalyzing HER in acidic media. Herein, we reported a novel hybrid nanostructure MoP/Co 2 P anchored on carbon fiber paper (CFP) (MoP/Co 2 P/CFP) which was achieved by a facile hydrothermal approach to obtain Co(CO 3 ) 0.35 Cl 0.20 (OH) 1.10 nanowires array (NA)/CFP, followed by deposition of MoO 2 nano-particles via chemical vapor deposition (CVD) in the presence of MoO 3 and a subsequent in situ phosphorization process. It was worth noting that the catalyst exhibited higher catalytic activity for HER in 0.5 M H 2 SO 4 solution, which afforded an overpotential of 140 mV at a current density of 10 mA cm À 2 , a Tafel slope of 80 mV dec À 1 , an exchange current density of 0.153 mA cm À 2 and a high electrochemical double-layer capacitance (C dl ) of 48.2 mF cm À 2 . Moreover, it also exhibited superior stability and durability in long-term durability test.[a] Prof. for 2 h under 10 % H 2 atmosphere with a temperature ramping rate of 5°C min À 1 . After cooling down to ambient temperature, the sample was washed with deionized water and ethanol for several times and dried naturally.
In this work, a cerium doped CoP nanoparticles (NPs) embedded in carbon nanotubes (CNTs) for efficient and durable hydrogen evolution was developed. The detailed preparation process was described as the followings. First, cerium was introduced into ZIF-67 to form Ce-doped ZIF-67 by a joint nucleation method. Then, the Ce-doped Co-CNTs was synthesized by carbonization of Ce-doped ZIF-67. During the process, the Co2+ was reduced to form Co NPs and the elegant nanostructure of CNTs was formed by the catalytic effect of Co NPs. Finally, by using Ce-doped Co-CNTs as the precursor, the target catalyst (Ce0.05-doped CoP CNTs) was obtained through a chemical vapour deposition (CVD) process in the presence of NaH2PO2. Results of the transmission electron microscopy (TEM) and scanning electron microscopy (SEM) showed that the target catalyst maintained the original rhombic dodecahedron morphology of ZIF-67 and the CoP NPs were embedded in CNTs and distributed uniformly throughout the catalyst. In electrochemical measurements, the catalyst showed the best performance for HER in 0.5 M H2SO4 solution. The onset potential, Tafel slope, electron transfer resistance (Rct) and double-layer capacitance (Cdl) of the target catalyst was 49 mV, 78 mV dec−1, 19.2 Ω and 10.5 mF cm−2, respectively. Meanwhile, the catalyst yielded a current density of 10 mA cm−2 merely at an overpotential of 146 mV. Furthermore, it maintained 90% of the original current density in a chronoamperometry measurement and showed no obvious decay even after 2000 cycles scans in a long-term durability test.
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