School of Materials Science and Engineering, Tianjin Key Laboratory of Composite and Functional Materials, Tianjin University, Tianjin 300072, China.
Nanoscale. 2019 Mar 21;11(12):5646-5654. doi: 10.1039/c8nr09902b.
The exploitation of economical and highly efficient bifunctional electrocatalysts to promote oxygen evolution and hydrogen evolution reactions (OER and HER) for water splitting devices is urgently needed. Herein, a series of NiSx (i.e., NiS, Ni3S2, NiS2) nanocrystals with controllable phase and composition have been synthesized via a facile polyol solution process and the corresponding electrocatalytic properties towards OER and HER have been systematically investigated. Electrochemical results reveal that Ni3S2 exhibits superior OER and HER performance to NiS and NiS2, achieving 1.63 V to reach a current density of 10 mA cm-2 in the overall water splitting device, which is comparable to that of noble metal catalysts. Experimental and theoretical calculation investigations demonstrate that the remarkable catalytic properties of Ni3S2 could be attributed to the intrinsic metallic conductivity, abundant active sites and optimal Gibbs free-energy for catalyst-H* for HER. Moreover, a thicker layer of catalytically active species of NiOOH was generated on the surface of Ni3S2 due to the higher proportion of Ni, leading to a better OER performance. These results should shed light on the design and development of low cost and efficient transition metal chalcogenide electrocatalysts through phase and composition regulation for advanced electrochemical energy conversion devices.
对于用于水分解装置的析氧反应 (OER) 和析氢反应 (HER) 的双功能电催化剂，迫切需要开发经济且高效的催化剂。在此，通过简单的多元醇溶液工艺合成了一系列具有可控相和组成的 NiSx（即 NiS、Ni3S2、NiS2）纳米晶体，并对其 OER 和 HER 电催化性能进行了系统研究。电化学结果表明，Ni3S2 具有优于 NiS 和 NiS2 的 OER 和 HER 性能，在整个水分解装置中达到 10 mA cm-2 的电流密度需要 1.63 V，这可与贵金属催化剂相媲美。实验和理论计算研究表明，Ni3S2 的显著催化性能可归因于其本征金属导电性、丰富的活性位点和对于 HER 的催化剂-H*的最佳吉布斯自由能。此外，由于 Ni 的比例较高，Ni3S2 表面生成了更厚的催化活性物种 NiOOH，从而表现出更好的 OER 性能。这些结果应该为通过相和组成调控设计和开发用于先进电化学能量转换装置的低成本、高效过渡金属硫属化物电催化剂提供思路。
