Dual‐Phase Engineering of Nickel Boride‐Hydroxide Nanoparticles toward High‐Performance Water Oxidation Electrocatalysts

The development of earth‐abundant and efficient oxygen evolution reaction (OER) electrocatalysts is necessary for green hydrogen production. The preparation of efficient OER electrocatalysts requires both the adsorption sites and charge transfer on the catalyst surface to be suitably engineered. Herein, the design of an electrocatalyst is reported with significantly enhanced water oxidation performance via dual‐phase engineering, which displays a high number of adsorption sites and facile charge transfer. More importantly, a simple chemical etching process enables the formation of a highly metallic transition boride phase in conjunction with the transition metal hydroxide phase with abundant adsorption sites available for the intermediates formed in the OER. In addition, computational simulations are carried out to demonstrate the water oxidation mechanism and the real active sites in this engineered material. This research provides a new material design strategy for the preparation of high‐performance OER electrocatalysts.     

Electrocatalytic performance of Pb−Ru pyrochlore prepared by the amorphous citrate precursor method for bifunctional air electrodes

Pb−Ru pyrochlore has been of interest as bifunctional electrocatalyst for an air electrode. An amorphous citrate precursor (ACP) process has been optimized to prepare Pb−Ru pyrochlore powders with high surface areas with consequent improvement of its electrocatalytic performance in an air electrode. The surface area of the final powder is 30 m²/g, which is larger than the value obtained by the conventional hydroxide method. A PTEF-bonded gas diffusion electrode loaded with pyrochlore catalysts prepared by the ACP method showed good bifunctional performance. The electrode loaded with only 10 mg/cm² of pyrochlore powder prepared by ACP showed good bifunctional performance, i.e. 100 mA/cm² for oxygen reduction and 100 mA/cm² for oxygen evolution, at 0.6 and 1.6 V vs. RHE, respectively. This performance compares well to the results from lower-area pyrochlore at much higher loading.     

酞菁催化剂对镍氢电池性能的影响

研究2种酞菁类催化剂——酞菁钴、酞菁铁作为负极添加剂对Ni-MH电池充放电、电池内压及循环性能的影响。结果表明：在负极材料中加入酞菁钴、酞菁铁能够显著提高电池充放电性能,1C充电至额定容量时,电池最高电压分别较对比电池降低25 mV和31 mV;5C放电时,中值电压分别较对比电池高45 mV和51 mV。电池的循环性能得到改善,0.5C循环150次时,分别剩余额定容量的75%和83%;电池安全性得到提高,电池内压显著降低。     

直接甲醇燃料电池的研究现状及技术进展

论述了直接甲醇燃料电池在各研究机构取得的最新进展。由于DMFC目前存在甲醇的电催化活性低和甲醇从阳极到阴极的渗透问题，从电催化剂及电解质膜等两个方面概述了DMFC目前对于关键技术的研究现状及进展情况，指出研究开发新型电催化剂和电解质膜可以提高DMFC的性能，同时指出了DMFC的发展方向及应用前景。     

液体进料直接甲醇燃料电池的电化学性能

采用循环伏安法、交流阻抗法和稳态电流 电压极化曲线法,研究了不同操作条件下液体进料直接甲醇燃料电池(DMFC)的放电性能,分析了甲醇浓度、电池工作温度和氧气压力对电极反应的影响。DMFC的放电性能因电池工作温度和氧气压力的提高而改善。增大甲醇浓度,阳极反应动力学性能改善,浓差极化被推迟,但甲醇穿透量同时增加。电池性能在甲醇浓度为2.0mol/L时达到最佳。     

Nanostructured silver catalyzed nickel foam cathode for an aluminum–hydrogen peroxide fuel cell

A nanostructured Ag catalyzed nickel foam cathode for an aluminum–hydrogen peroxide fuel cell was prepared using an electrodeposition technique. SEM images show that Ag nano-islands, about 2–3 μm in length and 100–200 nm in width are aligned on the surface of the Ni foam substrate. The composition of the catalyst layer of the cathode was examined by XRD. Electrochemical performance and stability of the cathode for the reduction of hydrogen peroxide in aluminum–hydrogen peroxide fuel cell were studied.     

A melamine formaldehyderesin route to in situ encapsulate Co2O3 into carbon black for enhanced oxygen reduction in alkaline media

Enhancing the activity and stability of the non-precious metal catalyst (NPMC) for oxygen reduction reaction (ORR) is vital for the commercialization of fuel cells. Herein, we put forward a method in which the melamine formaldehyderesin was used as a precursor to encapsulate in situ Co₂O₃ into carbon black to form Co₂O₃@MF-C catalysts. The prepared catalysts were characterized by TEM, XRD, XPS, BET, and Raman spectroscopy. The electrocatalytic activity was measured by using rotating disk electrode (RDE) voltammetry. The Co₂O₃@MF-Cs shows outstanding electrocatalytic activity in alkaline solution compared with the commercial Pt/C catalyst. The 20%Co₂O₃@MF-C-650 shows the highest activity for ORR and its initial reduction potential and half-wave potential reach 1.01 V and 0.94 V, respectively, in 0.1 M KOH solution. The prepared catalysts also follow the 4-electron pathway ORR process both in alkaline and in acid conditions.     

碱性介质中甲醇在PdRu/MWCNT上的电催化氧化

采用乙二醇还原法制备了碱性直接甲醇燃料电池Pd Ru/MWCNT阳极催化剂,并考察了其电催化性能。透射电子显微镜(TEM)结果显示,Ru的加入可以改善Pd纳米粒子在碳载体表面的分散性。X射线光电子能谱(XPS)显示,在Ru的作用下,金属Pd的氧化态有所升高。电化学测试结果表明,Pd Ru/MWCNT催化剂在碱性溶液中对甲醇电氧化反应具有较高的催化活性和较好的抗中毒能力。     

MoS2/硼掺杂石墨烯的电化学析氢和储锂性能

为了研发高效低成本的析氢反应(HER)电催化剂和高性能的电化学储锂电极材料,通过一步水热法制备MoS₂/硼掺杂石墨烯（MoS₂/BG）复合材料. 结果表明,少堆积MoS₂纳米片均匀地分散在硼掺杂石墨烯上,并具有较多的无序结构和扩大的层间距. 作为析氢反应电催化剂,MoS₂/BG复合材料表现出较高的电催化活性和较低的Tafel斜率（46.3 mV/dec）;作为电化学储锂电极材料,MoS₂/BG复合材料表现出优异的电化学储锂性能,可逆比容量为1 205 mA·h/g,并具有稳定的循环性能和显著增强的高倍率特性. MoS₂/BG复合材料电化学性能优异是由于硼掺杂改变石墨烯的电子性质和表面特性,以及无序结构较多的弱堆积MoS₂层均匀地分散在硼掺杂石墨烯表面,增加电催化析氢反应的活性位点和电化学储锂能力,降低电极反应的电子转移阻抗,增强电极反应的动力学性能.     

Effect of transition metal (M: Fe,Co or Mn) for the oxygen reduction reaction with non-precious metal catalysts in acid medium

The effect of the metal for the oxygen reduction reaction (ORR) in acid medium with non-precious metal catalysts has been investigated. A series of non-precious metal catalysts with typical formulation M/N/C with M being Mn, Co or Fe have been prepared by incorporating N onto an active carbon matrix by means of thermal treatments under inert atmospheres. The N-containing active carbons were further treated with the M-containing precursors based upon Mn, Co or Fe phthalocyanines and thermally treated under inert atmosphere. The performance for the ORR in acid medium of all of the catalysts has been evaluated by means of electrochemical techniques. The activity, both in terms of onset potential for the ORR and maximum current density at representative potentials between 900 and 700 mV follows the trend Fe > Co > Mn. In addition, the performance of the Fe-based catalysts obtained during the different stages of the catalyst preparation has been also evaluated. The catalysts obtained after the pyrolysis step are the only ones showing measurable rates for the ORR. Although the amount of N and Fe incorporated onto the carbon matrix decreases the pyrolysis treatment, this treatment leads to the formation of the real active sites for the ORR irrespectively of the nature of the transition metal.