具有经济性的碱性膜燃料电池氢气氧化反应催化剂

燃料电池是一种清洁高效的能量转换装置,可将储存在燃料中的化学能直接转化为电能。在过去的几十年中,燃料电池的开发取得了重大进展。聚合物电解质燃料电池,尤其是以质子交换膜燃料电池(PEMFC)为代表,可以实现高效率、高功率密度、快速启动,因而受到了广泛的关注。然而,PEMFC因使用昂贵的Pt基催化剂而导致成本较高,阻碍了其大规模的应用。近年来发展的碱性膜燃料电池(HEMFC)与PEMFC结构相似,但使用可传导氢氧根离子的聚合物电解质,并提供碱性工作环境。HEMFC由于具有使用非Pt电催化剂和较便宜双极板的可能性而备受关注。然而,HEMFC的一个巨大的挑战是阳极氢氧化反应(HOR)相对缓慢的动力学,这使得其需要较高载量的阳极催化剂才能实现较高的电池性能。因此,对于HEMFC而言,阳极催化剂的成本也很高,亟需开发在碱性条件下低成本、高活性和高稳定性的HOR催化剂。在本综述中,我们总结了HOR催化剂的最新研究进展,涉及文献中提出的各种HOR机理和催化剂,并分析了基于阳极催化剂成本的HEMFC性能。我们发现,最新报道的非Pt HOR催化剂可以降低阳极催化剂的成本,到达与PEMFC接近的成本水平。最后,我们对HOR的进一步研究进行了展望。

Electrochemical converting ethanol to hydrogen and acetic acid for large scale green hydrogen production

Electrochemical coupling hydrogen evolution with biomass reforming reaction(named electrochemical hydrogen and chemical cogeneration(EHCC)),which realizes green hydrogen production and chemical upgrading simultaneously,is a promising method to build a carbon-neutral society.Herein,we analyze the EHCC process by considering the market assessment.The ethanol to acetic acid and hydrogen approach is the most feasible for large-scale hydrogen production.We develop AuCu nanocatalysts,which can selectively oxidize ethanol to acetic acid(>97%)with high long-term activity.The isotopic and in-situ infrared experiments reveal that the promoted water dissociation step by alloying contributes to the enhanced activity of the partial oxidation reaction path.A flow-cell electrolyzer equipped with the AuCu anodic catalyst achieves the steady production of hydrogen and acetic acid simultaneously in both high selectivity(>90%),demonstrating the potential scalable application for green hydrogen production with low energy consumption and high profitability.

直接合成双掺杂N-MoP/N-CNT及其高效析氢催化性能（英文）

清洁氢能源是未来发展的重要方向,因此开发高效廉价的析氢材料尤为重要.掺杂的磷化物作为一种优异的析氢材料得到了广泛的关注.本文提出了一种将氮原子同时掺杂在磷化物催化剂和载体上的新的合成方法.在热处理的过程中,利用次磷酸铵(NH_4H_2PO_2)分解产生的氨和磷化氢气体与前驱体进行反应,一步得到双掺杂的氮掺杂碳纳米管负载氮掺杂磷化钼催化剂(N-MoP/N-CNT).该催化剂展现出了良好的析氢反应活性,当电流密度为10 mA cm^(-2)时,过电势只有103±5 mV,明显低于MoP纳米颗粒的过电势(243 mV).催化活性的提升主要来自掺氮带来的电子效应以及协同效应.该催化剂在电解水产氢方面具有应用前景.

Defective Ni_(3)S_(2)nanowires as highly active electrocatalysts for ethanol oxidative upgrading

Electrochemical upgrading of biomass ethanol to value-added chemicals is promising for sustainable society.Here,we synthesize defective Ni_(3)S_(2) nanowires(NWs),which show high activity towards electrochemical oxidation of ethanol to acetate.The Ni_(3)S_(2) NWs are formed by the oriented attachment mechanism,and rich defects are introduced during the growth.A low onset potential of 1.31 V and high mass activity of 8,716 mA·mgNi^(-1) at 1.5 V are achieved using the synthesized Ni_(3)S_(2) NWs toward the ethanol electro-oxidation,which are better than the Ni(OH)2 NWs and the Ni_(3)S_(2) nanoparticles(NPs).And the selectivity for the acetate generation is ca.99%.The high activity of Ni_(3)S_(2) NWs is attributed to the easier oxidation of Ni(II)to the catalytically active Ni(III)species with the promotion from S component and rich defects.These results demonstrate that the defective NWs can be synthesized by the oriented attachment method and the defective Ni_(3)S_(2) NWs structure as the efficient nonnoble metal electrocatalysts for oxidative upgrading of ethanol.

Ultrathin NiFeS nanosheets as highly active electrocatalysts for oxygen evolution reaction

The development of efficient and cost-effective oxygen evolution reaction(OER)electrocatalysts is crucial for clean energy conversion and storage devices,such as water-splitting,CO_(2) reduction,and metalair batteries.Herein,we report an efficient 2-dimensional OER catalyst of ultrathin nickel-iron sulfide nanosheets(Ni Fe S-NS).Dodecanethiol is employed in the synthesis,which prohibits the growth along the Z-axis,thus a nanosheet is obtained.The Ni Fe S-NS shows high OER catalytic activity,which only requires a small overpotential of 273 mV to achieve the OER current density of 10 mA/cm^(2) in alkaline electrolyte,and almost no decay after 150 h of chronopotentiometry test.The high performance is attributed to the 2-dimensional structure,the synergistic effect from the Ni and Fe components which promotes the formation of the high valence Ni species,and the tuning effect from the in-situ generated sulfate doping.This work demonstrates the advantages of the 2-dimensional sulfides in electrocatalysis.