掺杂石墨烯/过渡族金属化合物异质结构的构建及电化学催化析氢特性

Hydrogen energy is one of the cleanest energies, and electrochemical hydrogen evolution is an effective technique for hydrogen production. The catalytic abilities of noble metals such as Pt are very high, however, their costs are high and their resources are low in the world. Therefore, exploiting the catalysts with high performances and long-term stability is highly desirable in the field. Transition-metal compounds have been exhibited electrochemical hydrogen evolution ability, but there are still some issues those need to be addressed. First, poor conductivity leads to low efficiency of hydrogen evolution. Secondly, the mechanism about the hydrogen evolution is unclear. Thirdly, synergistic effects have been investigated scarcely. Fourthly, it is difficult to fabricate transition-metal compounds with a high pure phase such as metal carbides. In addition, it is necessary to explore the method to fabricate a film. A series of typical transition-metal compounds were designed, and incorporated with doped graphene to obtain heterostructures as high-performance and long-term stability of electrocatalysts towards hydrogen evolution. Their conductivities would be improved by the introduction of doped graphene, and synergistic effects would be investigated by controlling size, doping amount, phase composition and content of the catalysts, and the efficiency of the hydrogen evolution would be improved significantly; the corresponding mechanism would be clarified by DFT and X-ray absorption spectrum; their stabilities of hydrogen evolution would be enhanced by constructing a film. Therefore, scientific basis would be provided for the development and practical application of clean energies, and the development of the clean energy techniques would be promoted by the project.

氢能是最清洁的能源，电化学析氢是有效的制氢手段。铂等贵金属的催化活性较高，但价格昂贵，储量少。因此，探寻可替代贵金属的高效、稳定的催化剂是本领域发展的必然趋势。过渡族金属化合物表现出一定的电化学析氢特性，但还存在诸多亟待解决的关键科技问题：1）导电性差，催化剂析氢效率低。2）析氢机制尚不清晰。3）协同效应缺乏必要的研究。4）纯相过渡族金属化合物如碳化物等较难制备。此外，成膜技术有待开发。本项目拟设计合成一系列典型的过渡族金属化合物，并与掺杂石墨烯构建异质结构，作为高效、稳定的电化学析氢催化剂。通过引入掺杂石墨烯提高催化剂的导电性，通过控制催化剂尺寸、掺杂量、相组分、含量等因素，研究它们的协同效应，进而大幅提升其析氢效率；通过密度泛函理论与X-射线吸收谱等分析测试手段揭示其析氢机制；优化催化剂成膜技术提高其长期析氢稳定性。从而为清洁能源的发展及实际应用提供科学依据，推动清洁能源的快速发展。

氢气具有较大的燃烧热值，且无污染物产生，是目前最清洁的能源之一。电化学析氢是有效的制氢手段，同时也是某些清洁能源器件如燃料电池等的重要化学反应之一。铂等贵金属的催化活性较高，但价格昂贵，储量少，且在酸性溶液中化学稳定性不佳。因此，这些贵金属不适合与商业化应用。为了探求具有高活性、高稳定性以及低成本析氢催化剂，本项目设计合成一系列典型的过渡族金属化合物，并与具有良好导电性、掺杂的石墨烯相结合，构建掺杂石墨烯/过渡族金属化合物异质结构作为高效、稳定的电化学析氢催化剂。取得了如下研究成果：1）发展了空气气氛下，基于柯肯达尔效应的实验方法，制备了氮磷共掺杂石墨烯/中空磷化物、磷掺杂石墨烯/中空磷化物等、硫掺杂石墨烯/中空硫化物等，并可以实现量产；发展了球磨技术以及室温氮诱导的硼氮共掺活性炭/碳化物异质结构、硼氮共掺活性炭-氮掺杂石墨烯/碳化物异质结构和氮掺杂石墨烯/硼化物等；发展了溶剂热等技术制备了氮掺杂石墨烯/超小尺寸的氮化物等；2）发现了掺杂、形貌、金属组分以及尺寸对所制备的异质结构的析氢特性具有重要的调控作用；3）利用XRD、XPS、SEM、TEM等分析技术给出了析氢特性增强的原因，同时，对其析氢过程中形貌与组分的演变进行了研究，为后期的实际应用奠定了理论指导意义；4）研究了催化剂在大电流密度下如100mAcm-1以上的稳定性，初步研究了成膜技术，为后期的实际应用奠定了实验基础。本项目的研究为清洁能源的发展及实际应用提供依据，推动清洁能源的快速发展。