Academy of Scientific and Innovative Research (AcSIR), Ghaziabad201002, India.
Electrochemical Process Engineering (EPE) Division, CSIR-Central Electrochemical Research Institute (CECRI), Karaikudi630003, Tamil Nadu, India.
Inorg Chem. 2023 Feb 13;62(6):2726-2737. doi: 10.1021/acs.inorgchem.2c03840. Epub 2023 Jan 30.
Exploiting an affordable, durable, and high-performance electrocatalyst for the oxygen evolution reaction (OER) under lower pH condition (acidic) is highly challengeable and much attractive toward the hydrogen-based energy technologies. A spinel CoCrO is observed as a potential noble-metal-free candidate for OER in alkaline medium. The presence of Cr further leads to electronic structure modulation of CoO and thereby greatly increases the corrosive resistance toward OER in acidic environment. Herein, a typical CoCrO with three different morphologies was synthesized for the very first time and employed as an electrocatalyst for OER in alkaline (1 M KOH) and acidic (0.5 M HSO) medium. Moreover, different morphologies display a different intrinsic exposed active site and thereby display different electrocatalytic activities. Likewise, the CoCrO Mic (synthesized by the microwave heating method) displays a higher catalytic activity toward OER and delivers a low overpotential of 293 and 290 mV to attain 10 mA/cm current density and smaller Tafel slope values of 40 and 151 mV/dec, respectively, in alkaline and acidic environment than the synthesized CoCrO Wet (wet-chemically synthesized) and CoCrO Hyd (hydrothermally synthesized). Moreover, CoCrO Mic exhibits a long-term durability of 24 h (1 M KOH) and 10.5 h (0.5 M HSO). The optimized Co-O bond energy in OER condition makes the CoCrO Mic superior than the CoCrO Hyd and CoCrO Wet. Moreover, the substitution of Cr induces the electron delocalization around the Co active species and thereby, positive shifting of the redox potential leads to providing an optimal binding energy for OER intermediates. Also, interestingly, this work represents a catalytic activity trend by a simple experimental result without any complex theoretical calculation. The morphology-dependent electrocatalytic activity obtained in this work will provide a new strategy in the field of electrochemical conversion and energy storage application.
在较低 pH 值（酸性）条件下，开发一种经济实惠、耐用且高性能的电催化剂用于氧气析出反应（OER）极具挑战性，且对基于氢能的能源技术极具吸引力。尖晶石 CoCrO 被观察到是碱性介质中 OER 的一种潜在无贵金属候选物。Cr 的存在进一步导致 CoO 的电子结构调制，从而大大提高了其在酸性环境中的 OER 耐腐蚀性。在此，首次合成了三种不同形态的典型 CoCrO，并将其用作碱性（1 M KOH）和酸性（0.5 M HSO）介质中 OER 的电催化剂。此外，不同的形态显示出不同的内在暴露的活性位点，从而表现出不同的电催化活性。同样，CoCrO Mic（通过微波加热法合成）对 OER 表现出更高的催化活性，在碱性和酸性环境中分别达到 10 mA/cm 电流密度时，过电位仅为 293 和 290 mV，Tafel 斜率值分别为 40 和 151 mV/dec，优于合成的 CoCrO Wet（湿化学合成）和 CoCrO Hyd（水热合成）。此外，CoCrO Mic 表现出 24 h（1 M KOH）和 10.5 h（0.5 M HSO）的长期耐久性。在 OER 条件下优化的 Co-O 键能使 CoCrO Mic 优于 CoCrO Hyd 和 CoCrO Wet。此外，Cr 的取代诱导 Co 活性物种周围的电子离域，从而使氧化还原电位正向移动，为 OER 中间体提供最佳结合能。此外，有趣的是，这项工作代表了一种无需任何复杂理论计算的简单实验结果的催化活性趋势。本工作获得的形态依赖的电催化活性将为电化学转化和储能应用领域提供新的策略。
