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首页> 外文期刊>Energy & environmental science >Filling the oxygen vacancies in Co3O4 with phosphorus: an ultra-efficient electrocatalyst for overall water splitting
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Filling the oxygen vacancies in Co3O4 with phosphorus: an ultra-efficient electrocatalyst for overall water splitting

机译：用磷填充Co3O4中的氧空位：用于整体水分解的超高效电催化剂

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摘要

It is of essential importance to design an electrocatalyst with excellent performance for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in water splitting. Co3O4 has been developed as a highly efficient OER electrocatalyst, but it has almost no activity for HER. In a previous study, it has been demonstrated that the formation of oxygen vacancies (V-O) in Co3O4 can significantly enhance the OER activity. However, the stability of V-O needs to be considered, especially under the highly oxidizing conditions of the OER process. It is a big challenge to stabilize the V-O in Co3O4 while reserving the excellent activity. Filling the oxygen vacancies with heteroatoms in the V-O-rich Co3O4 may be a smart strategy to stabilize the V-O by compensating the coordination numbers and obtain an even surprising activity due to the modification of electronic properties by heteroatoms. Herein, we successfully transformed V-O-rich Co3O4 into an HER-OER electrocatalyst by filling the in situ formed V-O in Co3O4 with phosphorus (P-Co3O4) by treating Co3O4 with Ar plasma in the presence of a P precursor. The relatively lower coordination numbers in V-O-Co3O4 than those in pristine Co3O4 were evidenced by X-ray adsorption spectroscopy, indicating that the oxygen vacancies were created after Ar plasma etching. On the other hand, the relatively higher coordination numbers in P-Co3O4 than those in V-O-Co3O4 and nearly same coordination number as that in pristine Co3O4 strongly suggest the efficient filling of P in the vacancies by treatment with Ar plasma in the presence of a P precursor. The Co-O bonds in Co3O4 consist of octahedral Co3+(Oh)-O and tetrahedral Co2+(T-d)-O (Oh, octahedral coordination by six oxygen atoms and T-d, tetrahedral coordination by four oxygen atoms). More Co3+(Oh)-O are broken when oxygen vacancies are formed in V-O-Co3O4, and more electrons enter the octahedral Co 3d orbital than those entering the tetrahedral Co 3d orbital. Then, with the filling of P in the vacancy site, electrons are transferred out of the Co 3d states, and more Co2+(T-d) than Co3+(Oh) are left in P-Co3O4. These results suggest that the favored catalytic ability of P-Co3O4 is dominated by the Co2+(T-d) site. P-Co3O4 shows superior electrocatalytic activities for HER and OER (among the best non-precious metal catalysts). Owing to its superior efficiency, P-Co3O4 can directly catalyze overall water splitting with excellent performance. The theoretical calculations illustrated that the improved electrical conductivity and intermediate binding by P-filling contributed significantly to the enhanced HER and OER activity of Co3O4.
机译：设计一种对于水分解过程中的析氢反应（HER）和析氧反应（OER）均具有优异性能的电催化剂至关重要。 Co3O4已被开发为一种高效的OER电催化剂，但对HER几乎没有活性。在先前的研究中，已经证明在Co3O4中形成氧空位（V-O）可以显着增强OER活性。但是，需要考虑V-O的稳定性，尤其是在OER工艺的高度氧化条件下。在保留出色活性的同时，稳定Co3O4中的V-O是一个巨大的挑战。在富V-O的Co3O4中用杂原子填充氧空位可能是一种聪明的策略，可以通过补偿配位数来稳定V-O，并且由于杂原子对电子性质的改变而获得了令人惊讶的活性。在本文中，我们通过在P前驱物的存在下用Ar等离子体处理Co3O4，用磷（P-Co3O4）填充了Co3O4中原位形成的V-O，从而成功地将富含V-O的Co3O4转化为HER-OER电催化剂。 X射线吸收光谱法证明V-O-Co3O4中的配位数比原始Co3O4中的配位数低，这表明在Ar等离子刻蚀后产生了氧空位。另一方面，P-Co3O4中的配位数比VO-Co3O4中的配位数高，并且与原始Co3O4中的配位数几乎相同，这强烈表明在有碳原子存在的情况下，用Ar等离子体处理可以有效地填充空位中的P。 P的前体。 Co3O4中的Co-O键由八面体Co3 +（Oh）-O和四面体Co2 +（T-d）-O（Oh，由六个氧原子组成的八面体配位和T-d，由四个氧原子组成的四面体配位）组成。当在V-O-Co3O4中形成氧空位时，更多的Co3 +（Oh）-O被破坏，进入八面体Co 3d轨道的电子比进入四面体Co 3d轨道的电子更多。然后，通过在空位中填充P，电子被转移出Co 3d态，并且在P-Co3O4中残留的Co2 +（T-d）比Co3 +（Oh）多。这些结果表明，偏爱的P-Co3O4的催化能力主要由Co2 +（T-d）位点决定。 P-Co3O4对HER和OER（在最好的非贵金属催化剂中）显示出优异的电催化活性。由于其优异的效率，P-Co3O4可以直接催化整体水分解，并具有出色的性能。理论计算表明，通过P填充改善的电导率和中间结合显着有助于Co3O4的HER和OER活性增强。

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  • 来源
    《Energy & environmental science》 |2017年第12期|2563-2569|共7页
  • 作者

    Xiao Zhaohui; Wang Yu; Huang Yu-Cheng; Wei Zengxi; Dong Chung-Li; Ma Jianmin; Shen Shaohua; Li Yafei; Wang Shuangyin;

  • 作者单位

    Hunan Univ, State Key Lab Chem Biosensing & Chemometr, Coll Chem & Chem Engn, Changsha 410082, Hunan, Peoples R China;

    Nanjing Normal Univ, Coll Chem & Mat Sci, Nanjing 210023, Jiangsu, Peoples R China;

    Natl Synchrotron Radiat Res Ctr, 101 Hsin Ann Rd,Hsinchu Sci Pk, Hsinchu 30076, Taiwan;

    Hunan Univ, State Key Lab Chem Biosensing & Chemometr, Coll Chem & Chem Engn, Changsha 410082, Hunan, Peoples R China;

    Tamkang Univ, Dept Phys, 151 Yingzhuan Rd, New Taipei 25137, Taiwan;

    Hunan Univ, State Key Lab Chem Biosensing & Chemometr, Coll Chem & Chem Engn, Changsha 410082, Hunan, Peoples R China;

    Xi An Jiao Tong Univ, State Key Lab Multiphase Flow Power Engn, Xian 710049, Shaanxi, Peoples R China;

    Nanjing Normal Univ, Coll Chem & Mat Sci, Nanjing 210023, Jiangsu, Peoples R China;

    Hunan Univ, State Key Lab Chem Biosensing & Chemometr, Coll Chem & Chem Engn, Changsha 410082, Hunan, Peoples R China;

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