Kim Seongbeen, Choi Changhyeok, Hwang Jongkook, Park Jinkyu, Jeong Jooyoung, Jun Hyunwoo, Lee Seonggyu, Kim Soo-Kil, Jang Jong Hyun, Jung Yousung, Lee Jinwoo
Department of Chemical Engineering, Pohang University of Science and Technology (POSTECH), Pohang, Gyeongbuk 37673, Republic of Korea.
Department of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea.
ACS Nano. 2020 Apr 28;14(4):4988-4999. doi: 10.1021/acsnano.0c01285. Epub 2020 Mar 20.
To overcome inherent limitations of molybdenum carbide (MoC) for hydrogen evolution reaction (HER), , low density of active site and nonideal hydrogen binding strength, we report the synthesis of valence-controlled mesoporous MoC as a highly efficient HER electrocatalyst. The synthesis procedure uses an interaction mediator (IM), which significantly increases the density of active site by mediating interaction between PEO--PS template and Mo source. The valence state of Mo is tuned by systematic control of the environment around Mo by controlled heat treatment under air before thermal treatment at 1100 °C. Theoretical calculations reveal that the hydrogen binding is strongly influenced by Mo valence. Consequently, MoC achieves a significant increase in HER activity (exceeding that of Pt/C at high current density ∼35 mA/cm in alkaline solution). In addition, a volcano-type correlation between HER activity and Mo valence is identified with various experimental indicators. The present strategies can be applied to various carbide and Mo-based catalysts, and the established Mo valence and HER relations can guide development of highly active HER electrocatalysts.
为了克服碳化钼（MoC）在析氢反应（HER）中存在的固有局限性，即活性位点密度低和氢结合强度不理想的问题，我们报道了一种价态可控的介孔MoC的合成方法，它是一种高效的HER电催化剂。合成过程使用了一种相互作用介质（IM），通过介导PEO-PS模板与Mo源之间的相互作用，显著提高了活性位点的密度。通过在1100℃热处理之前在空气中进行可控热处理，系统地控制Mo周围的环境来调节Mo的价态。理论计算表明，氢结合受到Mo价态的强烈影响。因此，MoC在HER活性方面有显著提高（在碱性溶液中，在高电流密度约35 mA/cm²时超过了Pt/C）。此外，通过各种实验指标确定了HER活性与Mo价态之间的火山型相关性。目前的策略可以应用于各种碳化物和Mo基催化剂，并且所建立的Mo价态与HER之间的关系可以指导高活性HER电催化剂的开发。
