Florent Marc, Bandosz Teresa J
Department of Chemistry and Biochemistry, The City College of The City University of New York, 160 Convent Avenue, New York, NY 10031, USA.
Nanomaterials (Basel). 2022 Dec 13;12(24):4432. doi: 10.3390/nano12244432.
Highly porous carbon black and micro/mesoporous activated carbon were impregnated with cobalt and nickel nitrates, followed by heat treatment at 850 °C in nitrogen. Detailed information about chemistry and porosity was obtained using XPS, XRD, TEM/EDX, and nitrogen adsorption. The samples were used as ORR catalysts. Marked differences in the performance were found depending on the type of carbon. Differences in surface chemistry and porosity affected the chemistry of the deposited metal species that governed the O reduction efficiency along with other features of the carbon supports, including electrical conductivity and porosity. While dissociating surface acidic groups promoted the high dispersion of small metal species, carbon reactivity with oxygen and acidity limited the formation of the most catalytically active CoO. Formation of CoO on the highly conductive carbon black resulted in an excellent performance with four electrons transferred and a current density higher than that on Pt/C. When CoO was not formed in a sufficient quantity, nickel metal nanoparticles promoted ORR on the Ni/Co-containing samples. The activity was also significantly enhanced by small pores that increased the ORR efficiency by strongly adsorbing oxygen, which led to its bond splitting, followed by the acceptance of four electrons.
将高度多孔的炭黑和微孔/介孔活性炭用硝酸钴和硝酸镍浸渍，然后在氮气中于850℃进行热处理。使用XPS、XRD、TEM/EDX和氮吸附获得了有关化学性质和孔隙率的详细信息。这些样品用作氧还原反应（ORR）催化剂。根据碳的类型发现性能存在显著差异。表面化学性质和孔隙率的差异影响了沉积金属物种的化学性质，这些金属物种与碳载体的其他特性（包括电导率和孔隙率）一起决定了氧还原效率。虽然解离表面酸性基团促进了小金属物种的高度分散，但碳与氧的反应性和酸度限制了最具催化活性的CoO的形成。在高导电炭黑上形成CoO导致了优异的性能，有四个电子转移，电流密度高于Pt/C上的电流密度。当CoO没有足够量形成时，镍金属纳米颗粒促进了含镍/钴样品上的ORR。小孔也显著提高了活性，小孔通过强烈吸附氧气提高了ORR效率，导致氧的键断裂，随后接受四个电子。
