氮掺杂碳包埋钴纳米粒子电催化合成过氧化氢

电催化还原氧是一种新兴的可持续生产过氧化氢(H2O2)的合成技术,寻找低成本、高活性和高选择性的电催化剂是该技术实际应用的关键.钴氮掺杂的碳材料因含有钴氮(Co-Nx)催化活性位,成为一类新兴的可促进H2O2电化学合成的材料.本文采用低能耗干式球磨外加控制热解的方法来制备包含许多Co-Nx结构的钴氮掺杂碳材料.该方法使用材料廉价,即将醋酸钴、2-甲基咪唑和Ketjenblack EC-600JD高纯度且导电的碳黑分别作为金属、氮和碳的前体.在酸性介质中的电化学测试结果表明,该材料的氧还原反应电流密度明显增加,同时起始电位向正方向移动.该催化剂在较大电位范围内对H2O2的选择性约为90％.H2O2整体电解实验表明,H2O2产率达到100mmol gcat?1 h?1,H2O2法拉第效率达到85％(0.3Vvs.RHE条件下2h).耐久性测试(在0.3Vvs.RHE条件下6h)表明,催化剂表现出相对稳定的性能,且在整个测试循环中,法拉第效率达到约85％,表明催化剂在实际应用中具有良好的耐久性.催化剂表现出较高的电催化合成H2O2活性和选择性可能是由于形成了Co-Nx活性位,以及酸性环境和应用电位等其它因素的影响.

Electrocatalytic generation of hydrogen peroxide on cobalt nanoparticles embedded in nitrogen-doped carbon

Electrocatalytic reduction of oxygen is a growing synthetic technique for the sustainable production of hydrogen peroxide (H2O2). The current challenges concern seeking low-cost, highly active, and selective electrocatalysts. Cobalt-nitrogen-doped carbon containing catalytically active co-balt-nitrogen (Co-Nx) sites is an emerging class of materials that can promote the electrochemical generation of H2O2. Here, we report a straightforward method for the preparation of co-balt-nitrogen-doped carbon composed of a number of Co-Nx moieties using low-energy dry-state ball milling, followed by controlled pyrolysis. This scalable method uses inexpensive materials con-taining cobalt acetate, 2-methylimidazole, and Ketjenblack EC-600JD as the metal, nitrogen, and carbon precursors, respectively. Electrochemical measurements in an acidic medium show the present material exhibits a significant increase in the oxygen reduction reaction current density, accompanied by shifting the onset potential into the positive direction. The current catalyst has also demonstrated an approximate 90％selectivity towards H2O2 across a wide range of potential. The H2O2 production rate, as measured by H2O2 bulk electrolysis, has reached 100 mmol gcat.–1 h–1 with high H2O2 faradaic efficiency close to 85％(for 2 h at 0.3 V vs. RHE). Lastly, the catalyst durability has been tested (for 6 h at 0.3 V vs. RHE). The catalyst has shown relatively consistent performance, while the overall faradic efficiency reaches approximate 85％throughout the test cycle indicating the promising catalyst durability for practical applications. The formed Co-Nx moieties, along with other parameters, including the acidic environment and the applied potential, likely are the primary reasons for such high activity and selectivity to H2O2 production.