Phosphorus-Rich Metal Phosphides: Direct and Tin Flux-Assisted Synthesis and Evaluation as Hydrogen Evolution Electrocatalysts
Phosphorus-Rich Metal Phosphides: Direct and Tin Flux-Assisted Synthesis and Evaluation as Hydrogen Evolution Electrocatalysts
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DOI：
10.1021/acs.inorgchem.9b00032
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发表时间：
2019-04-15
影响因子：
4.6
通讯作者：
Gillan, Edward G.
中科院分区：
文献类型：
--
作者：
Coleman, Nathaniel, Jr.;Loyander, Matthew D.;Gillan, Edward G.
3d 时期的金属磷化物表现出一系列的结构和组成。许多富含金属的磷化物和单磷化物在析氢反应中充当非均相电催化剂。本文描述了具有 MP2 或 MP3 组合物的富磷金属磷化物的直接合成和锡助熔剂辅助合成。 FeP2、CoP3、NiP2 和 CuP2 的轻松合成是由无水金属卤化物和 P-4 蒸气在 500 摄氏度下反应形成 PCl3 的热化学驱动。这些无溶剂反应产生结晶良好的微米级颗粒。锡熔剂导致 FeP2 在较低温度下发生更完全的反应，并能够合成 NiP2 的单斜多晶型物，而不是通过直接反应形成的动态立方产物。研究这些结晶金属磷化物作为酸性和缓冲水溶液中析氢的电催化剂。所有富磷产品在强酸性介质中都表现出非常好的稳定性。在固定电极几何面积和低起始电位下，析氢催化活性按较高电流排序为 CoP3 > NiP2（立方晶系和单斜晶系） > FeP2 >> CuP2。在高电位下，CuP2 会发生表面反应和粗糙化，从而提高其电催化活性。对于这些富磷的 3d 金属磷化物，观察到的电催化活性与电化学活性表面积、粒径、金属与半导体性质以及局部金属配位环境的相关性。
Metal phosphides from the 3d period exhibit a range of structures and compositions. Many metal-rich phosphides and monophosphides function as heterogeneous electrocatalysts in the hydrogen evolution reaction. This paper describes the direct and tin flux-assisted synthesis of phosphorus-rich metal phosphides with MP2 or MP3 compositions. The facile synthesis of FeP2, CoP3, NiP2, and CuP2 is thermochemically driven by PCl3 formation from reactions of anhydrous metal halides and P-4 vapor at 500 degrees C. Well-crystallized micrometer-sized particles result from these solvent-free reactions. A tin flux leads to more complete reactions at lower temperature for FeP2 and enables synthesis of a monoclinic polymorph of NiP2 rather than the kinetic cubic product formed by direct reaction. These crystalline metal phosphides are investigated as electrocatalyts for hydrogen evolution in acidic and buffered aqueous solutions. All phosphorus-rich products show very good stability in strongly acidic media. The catalytic activity for hydrogen evolution ordered by higher current at a fixed electrode geometric area and low onset potential is CoP3 > NiP2 (cubic and monoclinic) > FeP2 >> CuP2. At high applied potentials, CuP2 undergoes surface reactions and roughening that improve its electrocatalytic activity. Correlations of the observed electrocatalytic activity with electrochemically active surface area, particle size, metallic versus semiconducting properties, and local metal coordination environment are noted for these phosphorus-rich 3d metal phosphides.