A series of N-doped carbon materials (NCs) were synthesized by using biomass citric acid and dicyandiamide as renewable raw materials via a facile one-step pyrolysis method. The characterization of microstructural features shows that the NCs samples are composed of few-layered graphene-like nanoflakes with controlled in situ N doping, which is attributed to the confined pyrolysis of citric acid within the interlayers of the dicyandiamide-derived g-C₃N₄ with high nitrogen contents. Evidently, the pore volumes of the NCs increased with the increasing content of dicyandiamide in the precursor. Among these samples, the NCs nanoflakes prepared with the citric acid/dicyandiamide mass ratio of 1:6, NC-6, show the highest N content of ~6.2 at%, in which pyridinic and graphitic N groups are predominant. Compared to the commercial Pt/C catalyst, the as-prepared NC-6 exhibits a small negative shift of ~66 mV at the half-wave potential, demonstrating excellent electrocatalytic activity in the oxygen reduction reaction. Moreover, NC-6 also shows better long-term stability and resistance to methanol crossover compared to Pt/C. The efficient and stable performance are attributed to the graphene-like microstructure and high content of pyridinic and graphitic doped nitrogen in the sample, which creates more active sites as well as facilitating charge transfer due to the close four-electron reaction pathway. The superior electrocatalytic activity coupled with the facile synthetic method presents a new pathway to cost-effective electrocatalysts for practical fuel cells or metal–air batteries.

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以生物质柠檬酸和双氰胺为可再生原料，通过简便的一步法热解法合成了一系列的N掺杂碳材料。微观结构特征的表征表明，NCs样品由几层石墨烯状纳米薄片组成，这些薄片中的N掺杂受到控制，这归因于柠檬酸在双氰胺衍生的gC ₃ N ₄的层间的局限性热解。氮含量高。显然，NCs的孔体积随着前驱物中双氰胺含量的增加而增加。在这些样品中，以柠檬酸/双氰胺质量比为1：6的NC-6纳米片NC-6显示最高的N含量约为6.2 at％，其中吡啶和石墨N基团占主导地位。与市售的Pt / C催化剂相比，所制备的NC-6在半波电势下表现出约66 mV的小负移，表明在氧还原反应中具有出色的电催化活性。此外，与Pt / C相比，NC-6还显示出更好的长期稳定性和耐甲醇穿透性。高效，稳定的性能归因于样品中类似石墨烯的微观结构以及吡啶和石墨掺杂氮的高含量，由于紧密的四电子反应路径，因此产生了更多的活性位点并促进了电荷转移。优异的电催化活性和简便的合成方法为实用的燃料电池或金属空气电池提供了一种具有成本效益的电催化剂的新途径。

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