Department of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, 610 Taylor Road, Piscataway, New Jersey, 08854, USA.
Department of Chemical and Biochemical Engineering, Rutgers, The State University of New Jersey, 98 Brett Road, Piscataway, 08854, New Jersey, USA.
Chempluschem. 2023 May;88(5):e202300104. doi: 10.1002/cplu.202300104. Epub 2023 Mar 23.
The development of durable and efficient electrocatalysts composed of low-cost, earth-abundant metals for the oxygen evolution reaction (OER) is crucial for industrial-scale water splitting to produce green hydrogen on a large scale. Transition metal borates are considered good candidate electrocatalysts for OER due to their low cost, ease of synthesis, and good catalytic activity. In this work, we demonstrate that the incorporation of an oxophilic main group metal, bismuth (Bi), into cobalt borates produces highly effective electrocatalysts for OER. We also show that the catalytic activity of Bi-doped cobalt borates can be improved further by pyrolyzing them in an argon atmosphere. During pyrolysis, the Bi crystallites formed in the materials melt, transform into amorphous phases, interact better with the Co or B atoms in there, and form more synergistic catalytic sites for OER. By varying the amount of Bi as well as the pyrolysis temperature, different Bi-doped cobalt borates are synthesized, and the most optimal OER electrocatalyst is identified. Among them, the one with Co : Bi ratio of 9 : 1 and that is pyrolyzed at 450 °C exhibits the best catalytic activity, driving the reaction at a current density of 10 mA cm with the lowest overpotential (318 mV) and a Tafel slope of 37 mV dec .
开发由低成本、地球丰富的金属组成的耐用且高效的电催化剂对于工业规模的水电解以大规模生产绿色氢气至关重要。由于成本低、合成容易和良好的催化活性，过渡金属硼酸盐被认为是 OER 的良好候选电催化剂。在这项工作中，我们证明了将亲氧主族金属铋 (Bi) 掺入钴硼酸盐中会产生用于 OER 的高效电催化剂。我们还表明，通过在氩气气氛中进行热解可以进一步提高 Bi 掺杂钴硼酸盐的催化活性。在热解过程中，材料中形成的 Bi 晶体熔化，转化为非晶相，与其中的 Co 或 B 原子更好地相互作用，并形成更多用于 OER 的协同催化位点。通过改变 Bi 的用量和热解温度，可以合成不同的 Bi 掺杂钴硼酸盐，并确定出最佳的 OER 电催化剂。其中，Co:Bi 比为 9:1 且在 450°C 下热解的样品表现出最佳的催化活性，在 10 mA cm 的电流密度下驱动反应，过电势最低（318 mV），塔菲尔斜率为 37 mV dec。
