强钴—氧键合作用提升缺陷型Co_(2)MnO_(4)酸性析氧反应稳定性  

Enhancing Cobalt―Oxygen Bond to Stabilize Defective Co_(2)MnO_(4) in Acidic Oxygen Evolution

作　　者：谢静宜 吕千喜 乔韦珍 卜辰宇 张昱声 翟雪君 吕仁庆[1] 柴永明[1] 董斌[1] Jingyi Xie;Qianxi Lü;Weizhen Qiao;Chenyu Bu;Yusheng Zhang;Xuejun Zhai;Renqing Lü;Yongming Chai;Bin Dong(State Key Laboratory of Heavy Oil Processing,College of Chemistry and Chemical Engineering,China University of Petroleum(East China),Qingdao 266580,Shandong Province,China)

机构地区：[1]中国石油大学(华东)化学化工学院,重质油全国重点实验室,山东青岛266580

出　　处：《物理化学学报》2024年第3期48-49,共2页Acta Physico-Chimica Sinica

基　　金：国家自然科学基金(52174283);中国石油大学(华东)研究生创新基金项目(22CX04023A);中央高校基本科研业务费资助。

摘　　要：通过实验和理论已经验证钴基氧化物是一种很有前景的析氧反应(OER)催化剂。然而,普通的钴基催化剂在酸性环境中非常不稳定,在酸性电解质中容易被腐蚀。因此,在目前的研究中,设计出能在强酸性条件下同时保持活性和稳定性的析氧催化剂是实现大规模工业制氢应用的一项重要挑战。因此,我们报道了通过在四氧化三钴的尖晶石晶格中引入锰(Mn)从而产生富含缺陷的催化剂(CoMn_(1)O),它在酸性电解质中具有较长的使用寿命。我们利用X射线衍射(XRD)、X射线光电子能谱(XPS)、高分辨率透射电子显微镜(HRTEM)和能量色散光谱(EDS)元素图研究了晶相结构和化学价态。在引入锰后,由于局部晶体结构的改变,产生了大量的缺陷。此外,随着锰含量的增加,可以观察到Co 2p光谱的红移,这表明Co的总价逐渐增加,形成了更稳定的Co-O键。此外,当Mn与Co的比例达到1(CoMn_(1)O)时,目标催化剂表现出良好的OER活性,在10和50mA·cm^(-2)时,过电位分别为415和552 mV。详细的物理表征和电化学测试表明,CoMn_(1)O比不含锰的Co_(3)O_(4)(CoMn_(0)O)能稳定4倍以上的时间。这可以归因于锰的引入调节了Co的电子密度偏向O,从而形成更稳定的Co-O键。Mn可以通过延缓Co活性位点的氧化速率来促进酸性氧的进化,并进一步提升稳定性。密度泛函理论(DFT)计算进一步分析了CoMn_(1)O和CoMn_(0)O的电子结构。与CoMn_(0)O相比,CoMn_(1)O中Co 3d的d带中心(εd)向费米能级(EF)移动。这表明CoMn_(1)O通过加强与OER中间物的键合作用从而降低了反应能垒。本研究为设计非贵金属电催化剂实现高效稳定的酸性析氧提供有前景的策略。Co-based oxides have shown promise as catalysts for the oxygen evolution reaction(OER),as evidenced by experimental and theoretical studies.However,these common Co-based catalysts suffer from poor stability in acidic environments,making them susceptible to corrosion in acid electrolytes.Consequently,developing OER catalysts that can maintain both activity and stability under strongly acidic conditions is a challenging task for large-scale industrial hydrogen production applications.To address this challenge,the incorporation of manganese(Mn)into the spinel lattice of Co_(3)O_(4)(CoMn_(1)O)has been proposed,resulting in a defectrich catalyst with improved lifetime in acidic electrolytes.The crystalline phase structures and chemical valence states were investigated using X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS),high-resolution transmission electron microscopy(HRTEM),and energy-dispersive spectroscopy(EDS)elemental maps.The introduction of Mn led to the generation of a significant number of defects due to changes in the local crystal structure.Additionally,as the amount of Mn atoms increased,a red shift was observed in the Co 2p spectrum,indicating an increase in the overall valence of Co and the formation of more stable Co―O bonds.Moreover,when the Mn-to-Co ratio reached 1(CoMn_(1)O),the resulting catalyst exhibited promising OER activity,with overpotentials of 415 and 552 mV at 10 and 50 mA·cm^(-2),respectively.Detailed physical characterization and electrochemical tests demonstrated that CoMn_(1)O exhibited over four times the stability of Mn-free Co_(3)O_(4)(CoMn_(0)O).This enhanced stability can be attributed to the introduction of Mn,which promotes electron density bias of Co towards O,resulting in the formation of more stable Co―O bonds.Mn also facilitates acidic oxygen evolution by delaying the oxidation rate of the Co active sites,thereby enhancing stability.Density functional theory(DFT)calculations were further employed to analyze the electronic structures of CoMn_(1)O and CoMn_(0

关 键 词：中空结构 钴锰尖晶石氧化物 钴锰普鲁士蓝类似物 酸性析氧反应 

分 类 号：O646[理学—物理化学]