In situ formation of nickel sulfide quantum dots embedded into a two-dimensional metal–organic framework for water splitting†
c
Yanzhong
Wang
*ab
Abstract
The synergistic interaction between metal–organic frameworks (MOFs) and transition metal sulfides (TMS) has been a research hotspot in the field of electrocatalytic water splitting. Herein, nickel sulfide quantum dots@NiFe-terephthalic acid nanosheet (NSQDs@NiFe-TPA) composites were prepared by a two-step hydrothermal method. The size and crystal structure of nickel sulfides were easily modulated by adjusting the concentration of the sulfurizing agent. The in situ formed NiS/Ni3S2 quantum dots with grain sizes of around 5 nm were evenly dispersed on the surface of NiFe-TPA nanosheets, and the overpotential was only 219 mV at 10 mA cm−2, and 90% current density could be maintained at 1.5 V (vs. RHE) for 60 h. When the concentration of the sulfurizing agent was increased up to 0.15 mmol L−1, the as-prepared Ni3S2@NiFe-TPA exhibited an excellent HER performance. The overpotential is only 109 mV to reach a current density of 10 mA cm−2, and it was attenuated by 20 mV after a 60 h stability test at a current density of 20 mA cm−2. Furthermore, the overall water-splitting electrolyzer assembled with NSQDs@NiFe-TPA and Ni3S2@NiFe-TPA as anodic and cathodic electrodes exhibited a low cell voltage of 1.66 V at a current density 10 mA cm−2, and almost no attenuation was observed after a 60 h stability test. The outstanding electrocatalytic properties of the as-prepared catalyst are due to the synergy of nickel sulfides and 2D MOFs that offers abundant accessible active sites, rapid ion/electron transportation, and convenient O2/H2 release channels.
- This article is part of the themed collections: FOCUS: Design and applications of metal-organic frameworks (MOFs) and Synthesis, modification and tailoring of properties of nanoporous materials
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