Yu Zi-You, Duan Yu, Gao Min-Rui, Lang Chao-Chao, Zheng Ya-Rong, Yu Shu-Hong
Division of Nanomaterials and Chemistry , Hefei National Laboratory for Physical Sciences at Microscale , Collaborative Innovation Center of Suzhou Nano Science and Technology , CAS Center for Excellence in Nanoscience , Hefei Science Center of CAS , Department of Chemistry , University of Science and Technology of China , Hefei , Anhui 230026 , P. R. China . Email:
Chem Sci. 2017 Feb 1;8(2):968-973. doi: 10.1039/c6sc03356c. Epub 2016 Sep 30.
The development of active, stable and low-cost electrocatalysts towards both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) for overall water splitting remains a big challenge. Herein, we report a new porous carbon-supported Ni/MoC (Ni/MoC-PC) composite catalyst derived by thermal treatment of nickel molybdate nanorods coated with polydopamine, which efficiently and robustly catalyses the HER and OER with striking kinetic metrics in alkaline electrolyte. The catalyst affords low onset potentials of -60 mV for the HER and 270 mV for the OER, as well as small overpotentials of 179 mV for the HER and 368 mV for the OER at a current density of 10 mA cm. These results compare favorably to MoC-PC, Ni-PC, and most other documented Ni- and Mo-based catalysts. The high activity of Ni/MoC-PC is likely due to electron transfer from Ni to MoC, leading to a higher Ni valence and a lower Mo valence in the Ni/MoC-PC catalyst, as these are HER and OER active species and thus account for the enhanced activity. Remarkably, our home-made alkaline electrolyser, assembled with Ni/MoC-PC as a bifunctional catalyst, can enable a water-splitting current density of 10 mA cm to be achieved at a low cell voltage of 1.66 V.
开发出对析氢反应（HER）和析氧反应（OER）均具有活性、稳定性且低成本的电催化剂以实现全水分裂仍然是一项巨大挑战。在此，我们报道了一种新型多孔碳负载的Ni/MoC（Ni/MoC-PC）复合催化剂，它由包覆聚多巴胺的钼酸镍纳米棒经过热处理衍生而来，在碱性电解质中能高效且稳定地催化HER和OER，并具有显著的动力学指标。该催化剂在HER方面的起始电位低至 -60 mV，在OER方面为270 mV，在电流密度为10 mA cm时，HER的过电位小至179 mV，OER的过电位为368 mV。这些结果优于MoC-PC、Ni-PC以及大多数其他已报道的镍基和钼基催化剂。Ni/MoC-PC的高活性可能归因于电子从Ni转移至MoC，导致Ni/MoC-PC催化剂中Ni的化合价升高而Mo的化合价降低，因为这些是HER和OER的活性物种，从而解释了活性的增强。值得注意的是，我们自制的以Ni/MoC-PC作为双功能催化剂组装的碱性电解槽，能在1.66 V的低电池电压下实现10 mA cm的全水分裂电流密度。
