Kundu Manas Kumar, Bhowmik Tanmay, Mishra Ranjit, Barman Sudip
School of Chemical Sciences, National Institute of Science Education and Research (NISER), Bhubaneswar, HBNI, Orissa-, 751 005, India.
ChemSusChem. 2018 Jul 20;11(14):2388-2401. doi: 10.1002/cssc.201800856. Epub 2018 Jul 4.
The design and synthesis of an active catalyst for the hydrogen evolution reaction/hydrogen oxidation reaction (HER/HOR) are important for the development of hydrogen-based renewable technologies. The synthesis of a hybrid of platinum nanostructures and nitrogen-doped carbon [Pt-(PtO )-NSs/C] for HER/HOR applications is reported herein. The HER activity of this Pt-(PtO )-NSs/C catalyst is 4 and 6.5 times better than that of commercial Pt/C in acids and bases, respectively. The catalyst exhibits a current density of 10 mA cm at overpotentials of 5 and 51 mV, with Tafel slopes of 29 and 64 mV dec in 0.5 m H SO and 0.5 m KOH. This catalyst also showed superior HOR activity at all pH values. The HER/HOR activity of Pt-(PtO )-NSs/C and PtO -free Pt-nanostructures on carbon (PtNSs/C) catalysts are comparable in acid. The presence of PtO in Pt-(PtO )-NSs/C makes this Pt catalyst more HER/HOR-active in basic media. The activity of the Pt-(PtO )-NSs/C catalyst is fivefold higher than that of the PtNSs/C catalyst in basic medium, although their activity is comparable in acid. The hydrogen-binding energy and oxophilicity are two equivalent descriptors for HER/HOR in basic media. A bifunctional mechanism for the enhanced alkaline HER/HOR activity of the Pt-(PtO )-NSs/C catalyst is proposed. In the bifunctional Pt-(PtO )-NSs/C catalyst, PtO provides an active site for OH adsorption to form OH , which reacts with hydrogen intermediate (H ), present at neighbouring Pt sites to form H O; this leads to enhancement of the HOR activity in basic medium. This work may provide an opportunity to develop catalysts for various renewable-energy technologies.
用于析氢反应/氢氧化反应（HER/HOR）的活性催化剂的设计与合成对于氢基可再生技术的发展至关重要。本文报道了用于HER/HOR应用的铂纳米结构与氮掺杂碳的杂化物[Pt-(PtO)-NSs/C]的合成。这种Pt-(PtO)-NSs/C催化剂在酸性和碱性条件下的HER活性分别比商业Pt/C高4倍和6.5倍。在0.5 m H₂SO₄和0.5 m KOH中，该催化剂在过电位为5和51 mV时表现出10 mA cm⁻²的电流密度，塔菲尔斜率分别为29和64 mV dec⁻¹。该催化剂在所有pH值下也表现出优异的HOR活性。Pt-(PtO)-NSs/C和无PtO的碳载铂纳米结构（PtNSs/C）催化剂在酸性条件下的HER/HOR活性相当。Pt-(PtO)-NSs/C中PtO的存在使这种铂催化剂在碱性介质中具有更高的HER/HOR活性。尽管Pt-(PtO)-NSs/C催化剂和PtNSs/C催化剂在酸性条件下活性相当，但在碱性介质中，Pt-(PtO)-NSs/C催化剂的活性比PtNSs/C催化剂高五倍。氢结合能和亲氧性是碱性介质中HER/HOR的两个等效描述符。提出了一种双功能机制来解释Pt-(PtO)-NSs/C催化剂增强的碱性HER/HOR活性。在双功能Pt-(PtO)-NSs/C催化剂中，PtO提供了一个OH吸附的活性位点以形成OH⁻，其与相邻Pt位点处存在的氢中间体（H*）反应形成H₂O；这导致碱性介质中HOR活性的增强。这项工作可能为开发用于各种可再生能源技术的催化剂提供机会。
