Physical and Materials Chemistry Division, CSIR-National Chemical Laboratory (CSIR-NCL), Pune 411008, India.
Phys Chem Chem Phys. 2018 Nov 28;20(46):29452-29461. doi: 10.1039/c8cp06641h.
Oxygen evolution is the key step in the oxidation of water in electrolyzers and photoelectrochemical cells for the production of hydrogen. Developing a non-precious metal oxide catalyst with good electrocatalytic activity for the oxygen evolution reaction (OER) is very challenging. In this work, nanostructured ZnxCo3-xO4 has been shown as an efficient catalyst with a low overpotential for the OER in 0.1 M KOH solution. Substitution of Co2+ in the spinel oxide Co3O4 with Zn2+ creates a higher number of high-spin Co3+, which is found to be directly correlated with the OER activity of ZnxCo3-xO4. Zn0.8Co2.2O4 (x = 0.8) with the optimum amount of Co2+/Co3+ and high-spin Co3+ content showed a very low overpotential of ∼250 mV, at 10 mA cm-2, with a turnover frequency of ∼3 × 10-3 s-1 for the OER. The high Faradaic efficiency along with the stability of Zn0.8Co2.2O4 and electrocatalytic activity comparable with that of precious metal oxides indicate that this composition is a promising catalyst for water oxidation.
氧析出是电解槽和光电化学电池氧化水以生产氢气的关键步骤。开发具有良好析氧反应（OER）电催化活性的非贵金属氧化物催化剂极具挑战性。在这项工作中，纳米结构的 ZnxCo3-xO4 被证明是一种在 0.1 M KOH 溶液中具有低过电位的高效 OER 催化剂。在尖晶石氧化物 Co3O4 中用 Zn2+取代 Co2+会产生更多的高自旋 Co3+，这与 ZnxCo3-xO4 的 OER 活性直接相关。具有最佳 Co2+/Co3+比例和高自旋 Co3+含量的 Zn0.8Co2.2O4（x = 0.8）在 10 mA cm-2 时表现出非常低的过电位约为 250 mV，OER 的周转频率约为 3 × 10-3 s-1。高法拉第效率以及 Zn0.8Co2.2O4 的稳定性和与贵金属氧化物相当的电催化活性表明，该组成是一种很有前途的水氧化催化剂。
