石墨烯负载纳米核壳结构N@M (N=Co, Ag; M=Au, Pt, Pd, Rh)复合催化剂的制备及其对甲酸分解脱氢的作用机理

Formic acid has recently attracted a great research interest in hydrogen storage due to its simplicity, high energy density and excellent stability at room temperature. However, lack of recyclable catalysts with high efficiency and excellent selectivity on the dehydrogenation reaction hinders its practical application. In this proposal, novel catalysts with core-shell structure N@M (N=Co, Ag; M=Au, Pt, Pd, Rh) anchored on graphene are proposed, prepared and systematically investigated for the dehydrogenation of formic acid. The relationship between the catalytic performance and the catalyst qualities such as distribution of particles, microstructure and composition is intensively explored by using TEM/EDS, XPS, XRD, UV-vis etc. techniques. Moreover, density functional theory (DFT) calculations are employed to acquire the thorough information on the elementary reactions, involved intermediate products and rate-limiting step in the dehydrogenation reaction. These studies will provide experimental evidence and theoretic basis for developing high efficient heterogeneous catalysts for dehydrogenation of formic acid. It is believed that the implementation of the proposal would greatly promote the practical application of formic acid system as mobile hydrogen storage material for fuel cells, which is of significant importance to solve the urgent atmospheric pollution issues.

甲酸储氢具有存储方便、能量密度高等优点，但目前限制其实际应用的关键在于缺乏一种可重复利用的催化甲酸选择性分解脱氢的高效催化剂。本项目拟利用液相法研究制备石墨烯负载纳米核壳结构N@M (N=Co, Ag; M=Au, Pt, Pd, Rh)复合催化剂用于催化甲酸脱氢反应，系统考察复合催化剂催化甲酸的选择性分解脱氢行为，综合运用TEM/EDS、XPS、XRD、UV-vis等测试方法分析颗粒分布、成分及微观结构变化等对其催化性能的影响规律，并结合第一性原理理论计算分析阐明催化剂催化甲酸脱氢反应中的基元反应、中间产物、速度控制步骤等，为研究开发甲酸分解脱氢的新型高效多相催化剂提供实验依据和理论基础。本项目的实施有助于促进甲酸等有机液态储氢材料在车载储氢方面的实用化进程，具有重要的科学意义和应用前景。

低温催化液态甲酸放氢是目前储氢材料领域的研究热点之一，其核心研究问题是如何实现在接近室温的温和条件下可控催化放氢，并尽可能的提高催化放氢的纯度以及高效催化剂的重复利用率。研究表明Pd等贵重金属由于其特殊的电子云分布和功函数，其催化效果最优。本项目针对不同单质贵重金属纳米颗粒与甲酸不同的作用机制，提出利用Ag等成本相对较低的金属与贵重金属Pd、Au等形成二元合金，进而改变其Pd、Au等金属电子云分布的特点，设计制备了负载于不同基体材料的不同二元纳米颗粒催化剂(空心球状Ag-Pd纳米球/石墨烯，Ag-Au，Au-Pd纳米颗粒@CNT等)，对其在催化放氢过程中的键合特征、微观结构演变、键态变化和催化放氢性能进行系统研究，查明体系的催化放氢反应机理。探索研究了不同二元纳米颗粒催化剂对甲酸催化放氢反应以及催化产生一氧化碳副反应的催化作用机理，并对负载基体材料对催化性能的影响进行了系统研究。在此基础上，探讨改善甲酸催化放氢的动力学作用机制，为此类新型液态储氢体系的开发应用奠定理论基础。