Abstract Considering the technological importance of the oxygen reduction reaction (ORR) and the cost constraints of highly catalytically active precious metals, recent research efforts have been focused on designing and synthesizing earth abundant non-precious metal catalysts for this reaction. Among recent advances in this area, transition metal-nitrogen modified tungsten carbides can be pointed as prominent candidates as ORR electrocatalysts. Nevertheless, mechanistically understandings of which active sites are responsible for the ORR electrocatalysis on these materials are required for the rational design of suitable materials. In the present work, various tungsten carbides and iron-nitrogen modified tungsten carbides catalysts are synthesized and in-depth characterized through various physical and electrochemical techniques towards gaining insights on the ORR process on these materials in both acidic and alkaline media. High performance materials are developed, with the most active presenting only a ca. 0.060 V increase in the ORR overpotential, compared to a standard platinum catalyst in an alkaline medium. The in-depth analyses allowed for suggestions on reaction pathways for the oxygen reduction on the hybrid Fe/N/WC/C nanomaterials in terms of active sites. These finds might direct further developments in the research on transition metal-nitrogen modified tungsten carbide materials.

中文翻译：

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氧还原电催化过渡金属-氮修饰碳化钨纳米材料

摘要 考虑到氧还原反应 (ORR) 的技术重要性和高催化活性贵金属的成本限制，最近的研究工作集中在为该反应设计和合成富含地球的非贵金属催化剂。在该领域的最新进展中，过渡金属 - 氮改性的碳化钨可以作为 ORR 电催化剂的突出候选物。然而，对于合适材料的合理设计，需要从机理上理解哪些活性位点负责这些材料的 ORR 电催化。在目前的工作中，合成各种碳化钨和铁氮改性碳化钨催化剂，并通过各种物理和电化学技术深入表征，以深入了解这些材料在酸性和碱性介质中的 ORR 过程。开发了高性能材料，最活跃的材料只有大约 与碱性介质中的标准铂催化剂相比，ORR 过电位增加了 0.060 V。深入分析允许就活性位点方面的杂化 Fe/N/WC/C 纳米材料的氧还原反应途径提出建议。这些发现可能会指导过渡金属-氮改性碳化钨材料研究的进一步发展。高性能材料被开发出来，最活跃的材料只有大约一个。与碱性介质中的标准铂催化剂相比，ORR 过电位增加了 0.060 V。深入分析允许就活性位点方面的杂化 Fe/N/WC/C 纳米材料的氧还原反应途径提出建议。这些发现可能会指导过渡金属-氮改性碳化钨材料研究的进一步发展。高性能材料被开发出来，最活跃的材料只有大约一个。与碱性介质中的标准铂催化剂相比，ORR 过电位增加了 0.060 V。深入分析允许就活性位点方面的杂化 Fe/N/WC/C 纳米材料的氧还原反应途径提出建议。这些发现可能会指导过渡金属-氮改性碳化钨材料研究的进一步发展。