通过二硫化钼的层间调控提高电催化加氢性能

电催化加氢反应能够在温和条件下生产高附加值化学品, 但受到析氢副反应和贵金属催化剂的制约。本工作首次通过铵根或烷基胺阳离子的原位插层, 发展高效的非贵金属加氢催化剂: 二硫化钼(MoS₂)。通过插层驱使MoS₂发生2H→1T相变, 有效地改善了其电子结构和表面疏水性, 促进了含氧生物质分子的电化学加氢反应, 并抑制了氢气的析出。在−0.25~−0.65 V(vs. RHE)电位范围内, 二甲胺阳离子插层的二硫化钼(MoS₂-DMA)能够高效电催化糠醛(FAL)合成糠醇, 法拉第效率高达86.3%~73.3%, 选择性>95.0%, 优于MoS₂和传统金属催化剂。该优越的加氢性能来源于催化剂对中间体较强的化学吸附和表面疏水性。该催化剂同时增强了关键反应物种Hads和FALads在边缘位点的化学吸附, 从而加快了表面速控步骤；同时, 疏水性的提高有利于FAL与电极材料接触, 克服扩散的限制。可见, 利用原位插层的方法能有效地调控MoS₂性质, 使得其从典型的析氢电催化剂转变为高效的电化学加氢催化剂, 这将拓宽电化学有机合成的催化剂开发思路。

暨南大学谭静雯博士为第一作者，高庆生教授为通讯作者，以题为“Interlayer engineering of molybdenum disulfide toward efficient electrocatalytic hydrogenation”发表于Science Bulletin 2021年第10期。

图文摘要

Fig. 1 Diagram and characterizations of MoS₂, MoS₂-A and MoS₂-DMA. (a) Schematic illustration for fabricating various MoS₂. (b) XRD patterns and (c, d, e) TEM images of (c) MoS₂, (d) MoS₂-A and (e) MoS₂-DMA. Insets of (c), (d) and (e) are their SEM images.

Fig. 2 Characterizations of MoS₂ with varied interlayer structures in control experiments. (a) XRD patterns of MoS₂ received with a low S/Mo feeding ratio of 2.0, and with additional NH₄Cl or (CH₃)₂NH₂Cl. (b) XRD patterns of MoS₂-DMA, MoS₂-DEA and MoS₂-DPA. (c) Schematic illustration for various intercalants and the corresponding interlayer structures. (d) Water CA test results.

Fig. 3  Characterization of MoS₂ phase transition from 2H to 1T along with interlayer expanding. (a) FT magnitudes of the k²[x(k)] EXAFS spectra and XPS profiles of (b) Mo and (c) S of MoS₂, MoS₂-A and MoS₂-DMA. (d) AC-TEM images and (e) HAADF-STEM images along with elemental mapping of MoS₂-DMA.

Fig. 4  Electrocatalytic performance of various MoS₂ along with the expanded interlayers. Polarization curves and Nyquist plots (at −0.45 V) of (a) MoS₂, (b) MoS₂-A, (c) MoS₂-DMA without and with 35 mM FAL. (d) FOL Faradaic efficiency, and (e) FAL conversion and FOL selectivity at different potentials. (f) Comparison of the ECH performance over various MoS₂ and metals at −0.25 V (CC: carbon cloth, Pt: commercial 40 wt% Pt/C loaded on CC, Ag: electrodeposited Ag on CC, Pd: Pd nanocrystals loaded on CC, Ni and Cu: commercial Ni and Cu foams).

Fig. 5  Theoretical calculation of the efficient FAL ECH on the MoS₂-DMA. (a) Electron density diagram and (b) PDOS of MoS₂, MoS₂-A and MoS₂-DMA. (c) HBE and FBE on the Mo and S sites of MoS₂, MoS₂-A and MoS₂-DMA models. The signs of (hkl)-Mo and (hkl)-S denote for the Mo and S sites on specific facets. (d) Comparison of three key factors (HBE, FBE and CA) of MoS₂, MoS₂ and MoS₂-DMA. The HBE and FBE on the Mo-sites of (100) plane are taken for comparison, because such sites have been identified effective for chemisorption and electrocatalysis.

Fig. 6   ECH of 5-HMF, CAL and p-NP over MoS₂-DMA operated at -0.25 V vs. RHE for 2 h, with Na₂B₄O₇ aqueous solution (pH 9.18) containing 0.035 mol/L substrate as the electrolyte.

 研究详情请阅原文：
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Jingwen Tan, Wenbiao Zhang, Yijin Shu, Haiyang Lu, Yi Tang, Qingsheng Gao. Interlayer engineering of molybdenum disulfide toward efficient electrocatalytic hydrogenation. Science Bulletin, 2021, 66(10): 1003-1012

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Science Bulletin是中国科学院主管、中国科学院和国家自然科学基金委员会共同主办、《中国科学》杂志社和Elsevier合作出版的自然科学综合性学术刊物，半月刊。报道范围主要涵盖物理学与天文学、化学、生命科学、医学科学、地球科学、材料科学、工程科学等新兴和前沿交叉学科。除Short Communication、Article、Perspective、Review等论文和评述类栏目外，还开设了News & Views、Research Highlight、Commentary、Correspondence等观点、消息类栏目。2020年影响因子11.780，位列全球73种多学科综合类期刊第7位，处于国际综合类期刊Q1区。中科院文献情报中心SCI期刊分区1区；中国科技期刊卓越行动计划领军期刊。