Luo Xiaohu, Zhang Lei, Guo Meng, Liu Zhen, Wu Dawang, Zhen Deshuai, Liu Yali
School of Chemistry and Chemical Engineering, Qiannan Normal University for Nationalities, Duyun558000, P. R. China.
State Key Laboratory for Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha410082, P. R. China.
ACS Appl Mater Interfaces. 2022 Oct 25. doi: 10.1021/acsami.2c15524.
Rational design of multi-structural defects in the transition-metal oxides is a very alluring and challenging strategy to significantly improve its oxygen evolution reaction (OER) performance. Herein, a simple and promising element doping approach is demonstrated to fabricate a poor-crystalline V-doping CuCoO (V-CuCoO) nanoneedle with rich oxygen vacancies (V), partially amorphous phase, and Co defects on the carbon fiber (CF) (V-CuCoO/CF). The results indicate that the V doping could further weaken the crystallinity of V-CuCoO, providing the thoroughfares for the convenience of electrolyte penetration and the exposure of active sites. Meanwhile, [CoO] octahedron in the V-CuCoO lattice is gravely distorted due to a strong electronic interaction between the doped V and Co atoms, creating more Co active species. With the merits of these multiple structural defects, V-CuCoO/CF exhibits rich active sites, and its intrinsically electrocatalytic activity is significantly enhanced. The optimized V-CuCoO/CF electrocatalyst has a significantly enhanced OER activity with a required low overpotential of ∼204 and ∼246 mV at a current density of 100 and 300 mA cm, respectively, a small Tafel slope of 40.7 mV dec, and excellent stability in an alkaline medium. Furthermore, the results from the projected partial density of states calculation not only demonstrate that the 3-fol-coordinated Co near V bonded with Cu and V sites (Cu-Co-V) exhibits an enhanced electronic transfer activity but also reveal that the doped V could protect the Co sites from the deactivation by intermediates overbinding on the V sites. This work provides new insights into structure engineering of spinel phase copper cobaltite, resulting in significantly boosting electrocatalytic OER activity.
合理设计过渡金属氧化物中的多重结构缺陷是一种极具吸引力且具有挑战性的策略，可显著提高其析氧反应（OER）性能。在此，展示了一种简单且有前景的元素掺杂方法，用于在碳纤维（CF）上制备具有丰富氧空位（V）、部分非晶相和Co缺陷的结晶性较差的V掺杂CuCoO（V-CuCoO）纳米针（V-CuCoO/CF）。结果表明，V掺杂可进一步削弱V-CuCoO的结晶度，为电解质渗透和活性位点暴露提供通道。同时，由于掺杂的V和Co原子之间强烈的电子相互作用，V-CuCoO晶格中的[CoO]八面体严重扭曲，产生更多的Co活性物种。凭借这些多重结构缺陷的优点，V-CuCoO/CF展现出丰富的活性位点，其本征电催化活性显著增强。优化后的V-CuCoO/CF电催化剂具有显著增强的OER活性，在电流密度为100和300 mA cm时，所需的低过电位分别约为204和246 mV，塔菲尔斜率为40.7 mV dec，并且在碱性介质中具有出色的稳定性。此外，投影态密度计算结果不仅表明与Cu和V位点键合的V附近的三配位Co（Cu-Co-V）表现出增强的电子转移活性，还揭示了掺杂的V可以保护Co位点免受中间体在V位点上过度结合而失活。这项工作为尖晶石相铜钴矿的结构工程提供了新的见解，从而显著提高了电催化OER活性。
