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Significantly Improved Water Oxidation of CoP Catalysts by Electrochemical Activation
ACS Sustainable Chemistry & Engineering ( IF 7.1 ) Pub Date : 2020-11-19 , DOI: 10.1021/acssuschemeng.0c07169 Pengxia Ji 1, 2 , Xu Luo 1 , Ding Chen 1 , Huihui Jin 1 , Zonghua Pu 1 , Weihao Zeng 1 , Jianwei He 1 , Huawei Bai 1 , Yucong Liao 1 , Shichun Mu 1, 2
ACS Sustainable Chemistry & Engineering ( IF 7.1 ) Pub Date : 2020-11-19 , DOI: 10.1021/acssuschemeng.0c07169 Pengxia Ji 1, 2 , Xu Luo 1 , Ding Chen 1 , Huihui Jin 1 , Zonghua Pu 1 , Weihao Zeng 1 , Jianwei He 1 , Huawei Bai 1 , Yucong Liao 1 , Shichun Mu 1, 2
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The key to realizing highly efficient hydrogen production by water electrolysis is to elevate the electrocatalytic activity of the oxygen evolution reaction (OER) as a rate-determining step. Herein, we demonstrate that the electrochemical activation process of the CoP nanoflower supported on carbon cloth (CoP/CC) can remarkably reduce the OER overpotential by about 123 mV, which only requires an ultralow overpotential of 176 mV at the current density of 10 mA cm–2. Correspondingly, the voltage of the assembled CoP/CC||CoP/CC electrolyzer is also greatly decreased from 1.64 to 1.49 V at 10 mA cm–2. We further find that during the OER process, at least a three-step electro-oxidation process occurs on the catalyst surface in different potential ranges: under lower potentials, the ultrathin CoP nanosheets are oxidized to divalent CoO, then further oxidized to trivalent β-CoOOH under moderate potentials, and even transformed to CoIV species under high potentials. Such produced oxidized species are favorable to the formation of OOH* active intermediates or directly serve as OOH* active intermediates of the rate-determining step, thus facilitating the OER process. Meanwhile, the generation of porous surfaces, downsizing particles, active intermediate crystal structures, and new interfaces during the OER activation process can also lower the energy barrier, further accelerating the OER process.
中文翻译：
通过电化学活化显着改善CoP催化剂的水氧化性能
通过水电解实现高效制氢的关键是提高氧释放反应（OER）的电催化活性，这是决定速率的步骤。在本文中，我们证明了碳布（CoP / CC）上负载的CoP纳米花的电化学活化过程可以显着降低OER超电势约123 mV，在电流密度为10 mA cm时仅需要176 mV的超低超电势。–2。相应地，组装的CoP / CC ||| CoP / CC电解槽的电压在10 mA cm –2时也从1.64 V大大降低到1.49 V。我们进一步发现，在OER过程中，催化剂表面上至少在不同电位范围内发生了三步电氧化过程：在较低的电位下，超薄CoP纳米片被氧化为二价CoO，然后进一步被氧化为三价β- CoOOH在中等电位下，甚至在高电位下转化为Co IV物种。此类产生的氧化物质有利于OOH *活性中间体的形成，或直接用作速率确定步骤中的OOH *活性中间体，因此有助于OER工艺。同时，在OER活化过程中产生多孔表面，减小颗粒尺寸，激活中间晶体结构和新界面也可以降低能垒，从而进一步加速OER过程。
更新日期：2020-12-07
中文翻译：
通过电化学活化显着改善CoP催化剂的水氧化性能
通过水电解实现高效制氢的关键是提高氧释放反应（OER）的电催化活性，这是决定速率的步骤。在本文中，我们证明了碳布（CoP / CC）上负载的CoP纳米花的电化学活化过程可以显着降低OER超电势约123 mV，在电流密度为10 mA cm时仅需要176 mV的超低超电势。–2。相应地，组装的CoP / CC ||| CoP / CC电解槽的电压在10 mA cm –2时也从1.64 V大大降低到1.49 V。我们进一步发现，在OER过程中，催化剂表面上至少在不同电位范围内发生了三步电氧化过程：在较低的电位下，超薄CoP纳米片被氧化为二价CoO，然后进一步被氧化为三价β- CoOOH在中等电位下，甚至在高电位下转化为Co IV物种。此类产生的氧化物质有利于OOH *活性中间体的形成，或直接用作速率确定步骤中的OOH *活性中间体，因此有助于OER工艺。同时，在OER活化过程中产生多孔表面，减小颗粒尺寸，激活中间晶体结构和新界面也可以降低能垒，从而进一步加速OER过程。
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