中文摘要：

以噻吩和苯为硫源和碳源、以MgO为模板,通过化学气相沉积法制得了硫掺杂碳纳米笼,具有比表面积大、孔道结构丰富和石墨化程度较好等特点.通过改变噻吩的用量可在0～3.45 at％范围内调变其硫掺杂量.系统考察了硫的掺杂量对于碳纳米笼氧还原性能的影响,结果表明：硫含量为0.84 at％的SCNCs具有最佳的氧还原性能,随着硫掺杂量增多其氧还原性能逐渐变差,当硫的掺杂量高于1.61 at％时甚至不如未掺杂的碳纳米笼.这对于通过调变掺杂元素种类、含量及掺杂构型优化碳基无金属氧还原催化剂具有参考价值.

英文摘要：

The sluggish oxygen reduction reaction （ORR） is the bottleneck in the development of fuel cells, and replacing precious and nondurable Pt catalysts by the material with low cost, high activity and good stability is a main challenge. Carbon-based metal-free ORR electrocatalysts have become a promising alternative of commercial Pt/C catalyst due to their superior catalytic activity, high stability and low cost. Recent studies revealed that the doping of N, B, P or S atoms could boost the ORR electrocatalytic performance of carbon nanomaterials, and the catalytic activities were highly dependent on the doping elements, amounts and microstructures. In this study, sulfur-doped carbon nanocages （SCNCs） were synthesized by chemical vapor deposition method using in situ generated MgO as template and thiophene/benzene as precursors. The resultant SCNCs possessed high specific surface area of ca. 1000 m2·g^-1, abundant pore structure and superior graphitization degree. The X-ray photoelectron spectroscopy result showed sulfur atoms were doped into the carbon framework as the C-- S--C moieties. The content of sulfur in the SCNCs was adjusted in the range of 0-3.45 at% by changing the amount of thiophene in the precursor. All the SCNCs samples had comparable specific surface area and similar pore structure. As an electrocatalyst for oxygen reduction reaction （ORR） in alkaline medium, the SCNCs exhibited a sulfur-content-dependent performance. The SCNCs with sulfur content of 0.84 at% demonstrated the optimal ORR performance. With further increasing the sulfur content, the ORR performance of the SCNCs gradually degraded and even inferior to that of the pure CNCs when the sulfur content was higher than 1.61 at%. In addition, the SCNCs showed better stability and immunity to methanol crossover than the Pt/C catalyst. This result is suggestive for designing advanced metal-free ORR electrocatalysts by regulating the species and content of dopants and doping microstructures.