Singh Chandani, Haldar Atanu, Basu Olivia, Das Samar K
School of Chemistry, University of Hyderabad, Hyderabad 500046, India.
Inorg Chem. 2021 Jul 19;60(14):10302-10314. doi: 10.1021/acs.inorgchem.1c00734. Epub 2021 Jun 29.
Hydrogen is the solution to all the problems associated with the energy crisis. Generating hydrogen from water splitting is one of the greener approaches, but it requires an efficient catalyst that is economical for the bulk production of hydrogen. The transition metal-aqua coordination complexes, which are otherwise inactive/unstable for electrochemical hydrogen evolution reaction (HER) activity, can efficiently be utilized for the same by attaching these metal-aqua species on a stable support. With a similar approach, we have synthesized and structurally characterized a two-dimensional polyoxometalate (POM)-copper complex hybrid that supports a copper(II)-aqua-bypyridine complex with a molecular formula of the overall system, [{Cu(2,2'-bpy)(HO)}][{CoWO}{Cu(2,2'-bpy)(HO)}{Cu(2,2'-bpy)}]·2HO (). The bis(aqua)-mono(bipyridine) Cu(II)-complex fragment {Cu(2,2'-bpy)(HO)}, attached to the two-dimensional POM-Cu-complex support, acts as an active catalytic center that catalyzes the electrochemical HER. The electrochemical studies done for this work enabled us to understand the role of compound as an electrocatalyst for the HER in near-neutral medium (pH 4.8), under buffered conditions (acetate buffer). Through detailed electrochemical experiments including controlled ones, we understand that compound follows a proton-coupled electron transfer (PCET) pathway with one proton and one electron involvement in the HER. The overpotential required to achieve a current density of 1 mA/cm is found to be 520 mV with a Faradaic efficiency of 81%.
氢是解决与能源危机相关的所有问题的办法。通过水分解来制氢是较为环保的方法之一，但这需要一种高效且经济的催化剂来大规模生产氢气。过渡金属 - 水配位络合物对于电化学析氢反应（HER）活性原本是无活性/不稳定的，但通过将这些金属 - 水物种附着在稳定的载体上，就可以有效地用于该反应。采用类似的方法，我们合成并对一种二维多金属氧酸盐（POM） - 铜络合物杂化物进行了结构表征，该杂化物负载了一种铜（II） - 水 - 联吡啶络合物，整个体系的分子式为[{Cu(2,2'-bpy)(H₂O)}][{CoWO₄}{Cu(2,2'-bpy)(H₂O)}{Cu(2,2'-bpy)}]·2H₂O 。附着在二维POM - 铜络合物载体上的双（水） - 单（联吡啶）铜（II） - 络合物片段{Cu(2,2'-bpy)(H₂O)}充当催化电化学析氢反应的活性催化中心。针对这项工作所做的电化学研究使我们能够了解该化合物在近中性介质（pH 4.8）、缓冲条件（醋酸盐缓冲液）下作为析氢反应电催化剂的作用。通过包括对照实验在内的详细电化学实验，我们了解到该化合物在析氢反应中遵循质子耦合电子转移（PCET）途径，有一个质子和一个电子参与反应。发现实现1 mA/cm²电流密度所需的过电位为520 mV，法拉第效率为81%。
