稀土金属助催的甲醇水蒸汽重整制氢催化剂的研究

制备稀土金属离子助催的铜锌基甲醇水蒸汽重整催化剂并分别比较了铜锌和两种以稀土Ce3+,Zr4+为助催剂的铜锌催化剂上甲醇水蒸汽重整制氢的催化性能:在220℃反应条件下,Cu ZnO,Cu ZnO Ce2O3和Cu ZnO ZrO2的甲醇转化率分别为28.1%、37.3%和51.6%,后两个催化剂的氢选择性高达100%,CO的选择性为0.Cu ZnO ZrO2催化剂经60h的运转后,催化剂的性能不变,触氧实验表明该催化剂能满足甲醇燃料电池电动车启动温度低、CO2选择性高的要求.

Theoretical On-Board Hydrogen Redox Electric Power Generator for Infinite Cruising Range Fuel Cell Vehicles

The development of hydrogen redox electric power generators for infinite cruising range electric vehicles represents a true technological breakthrough. Such systems consist of a polymer electrolyte membrane hydrogen electrolytic cell equipped with an electrostatic-induction potential-superposed water electrolytic cell that provides a stoichiometric H2-O2 fuel mixture during operation of the vehicle. This generator functions with zero power input, zero matter input and zero emission due to the so-called ＂zero power input＂ electrostatic-to-chemical energy conversion occurring in the electrolytic cell. Here, theoretical simulations were performed to verify the target performance of such generators, assuming a pair of FC （fuel cell） and electrolytic cell stacks, both of which are commercially available.

石墨炔在电化学储能器件中的应用研究

石墨炔作为一种新型二维碳材料,具有π共轭单元、sp^(2)和sp杂化的碳原子和可调节的孔结构,结构稳定,导电性好,可塑性强。简要介绍了不同类型的石墨炔及其结构,阐述了石墨炔及其衍生物的合成策略,重点综述了石墨炔及石墨炔衍生物在能源领域的研究内容和成果,介绍了石墨炔及其衍生物在锂离子电池、氢-氧燃料电池、钠离子电池、超级电容器和其它一些电化学储能器件及材料上的研究成果。综合分析表明,石墨炔在电化学储能器件方面具有广阔的应用前景。

Carbon supported IrM(M= Fe,Ni,Co) alloy nanoparticles for the catalysis of hydrogen oxidation in acidic and alkaline medium

We studied the alloying effect in lr-based alloys on the catalysis of the hydrogen oxidation reaction （HOP,） in both acidic and alkaline medium. IrFe, lrNi and IrCo alloy catalysts with nanoparticle size of 〈S nm were obtained by our solvent-vaporization plus hydrogen reduction method. The second metal played an important role in tuning the crystal structure and surface electronic structure of the Ir-based alloy catalyst. Among the lrFe, IrCo and lrNi alloy catalysts, Ni induced a mid-sized contrac- tion of the lr lattice, and gave the best HOR activity in both acidic and alkaline medium. In acidic medium, the weakening of the Ir-Had interaction caused by the electronic effect of M （M = Fe, Ni, Co） alloying is responsible for the enhancement of HOR activity. The oxophilic effect of the catalytic metal surface, which affects OHad adsorption and desorption and surface Had coverage, has a large impact on the HOR activity in the case of alkaline medium,

Catalytic activity of V_(2)CO_(2) MXene supported transition metal single atoms for oxygen reduction and hydrogen oxidation reactions:A density functional theory calculation study

Two-dimensional(2D)MXene and single-atom(SA)catalysts are two frontier research fields in catalysis.2D materials with unique geometric and electronic structures can modulate the catalytic performance of supported SAs,which,in turn,affect the intrinsic activity of 2D materials.Density functional theory calculations were used to systematically explore the potential of O-terminated V2C MXene(V_(2)CO_(2))-supported transition metal(TM)SAs,including a series of 3d,4d,and 5d metals,as oxygen reduction reaction(ORR)and hydrogen oxidation reaction(HOR)catalysts.The combination of TM SAs and V_(2)CO_(2)changes their electronic structure and enriches the active sites,and consequently regulates the intermediate adsorption energy and catalytic activity for ORR and HOR.Among the investigated TM-V_(2)CO_(2)models,Sc-,Mn-,Rh-,and PtMCCh showed high ORR activity,while Sc-,Ti-,V-,Cr-,and Mn-V_(2)CO_(2)exhibited high HOR activity.Specifically,Mn-and Sc-V_(2)CO_(2)are expected to serve as highly efficient and cost-effective bifunctional catalysts for fuel cells because of their high catalytic activity and stability.This work provides theoretical guidance for the rational design of efficient ORR and HOR bifunctional catalysts.

Electrocatalysts development for hydrogen oxidation reaction in alkaline media:From mechanism understanding to materials design

Anion exchange membrane(AEM)fuel cells have gained great attention partially due to the advantage of using non-precious metal as catalysts.However,the reaction kinetics of hydrogen oxidation reaction(HOR)is two orders of magnitude slower in alkaline systems than in acid.To understand the slower kinetics of HOR in base,two major theories have been proposed,such as(1)pH dependent hydrogen binding energy as a major descriptor for HOR;and(2)bifunctional theory based on the contributions of both hydrogen and hydroxide adsorption for HOR in alkaline electrolyte.Here,we discuss the possible HOR mechanisms in alkaline electrolytes with the corresponding change in their Tafel behavior.Apart from the traditional Tafel-Volmer and Heyrovsky-Volmer HOR mechanisms,the recently proposed hydroxide adsorption step is also discussed to illustrate the difference in HOR mechanisms in acid and base.We further summarize the representative works of alkaline HOR catalyst design(e.g.,precious metals,alloy,intermetallic materials,Ni-based alloys,carbides,nitrides,etc.),and briefly describe their fundamental HOR reaction mechanism to emphasize the difference in elementary reaction steps in alkaline medium.The strategy of strengthening local interaction that facilitates both H2 desorption and Hads+OHads recombination is finally proposed for future HOR catalyst design in alkaline environment.

Modelling the Hydrogen Inhibition Effect on Ammonia Decomposition

Recently ammonia has been investigated as a fuel for SOFCs （solid oxide fuel cells）. Ammonia is widely produced and transported globally, and stores hydrogen in its bonds making it an excellent fuel for fuel cells. The high temperature of SOFCs allows for internal decomposition of ammonia. Previous models of ammonia-fed SOFCs treat ammonia decomposition as having first order dependence on ammonia partial pressure, and ignore the effect of hydrogen inhibition. However, research has shown that at low temperatures （≤ 600 ℃） and low ammonia partial pressures, the rate of ammonia decomposition is inhibited by the presence of hydrogen. This hydrogen inhibition effect was studied and implemented in a model of an ammonia decomposition reactor. Results showed that it may significantly decrease the rate of hydrogen generation. This work sets the foundation for more accurate modelling of intermediate temperature ammonia-fed SOFCs.

Self-healing and highly elastic fluorine-free proton exchange membranes comprised of poly(vinyl alcohol) derivative and phytic acid for durable fuel cells

Fluorine-free proton exchange membranes(PEMs)capable of healing from physical damage are important for PEM fuel cells(PEMFCs)with extended service life and enhanced reliability.Herein,highly elastic fluorine-free PEMs with excellent self-healing ability and high proton conductivity are fabricated through complexation of phytic acid(PA)with sulfonated polyvinyl alcohol(SPVA),followed by subsequent grafting of SPVA with positively charged 4-(1H-imidazol-1-yl)benzenecarbaldehyde(IBZ).Compared with recast Nafion membranes,the as-prepared SPVA-IBZ/PA membranes exhibit an enhanced mechanical strength and elasticity and can spontaneously recover from a^50%strain to their initial states within^30 s at room temperature.Meanwhile,the SPVA-IBZ/PA membranes have a proton conductivity of^0.095 S cm-1at^70°C,which is higher than that of recast Nafion membranes.The hydrogen-powered PEMFCs using the SPVA-IBZ/PA membranes,which show an open circuit voltage of^0.98 V and maximum power density of^609 mW cm-2,exhibit a satisfactory cell performance.Importantly,the SPVA-IBZ/PA membranes can spontaneously heal mechanical damage of several tens of micrometers in size and restore their original proton conductivity and cell performance under the working conditions of PEMFCs.

Converting biomass into efficient oxygen reduction reaction catalysts for proton exchange membrane fuel cells

It is urgent to develop low-cost but efficient oxygen reduction reaction(ORR)catalysts for the emerging clean energy devices of fuel cells based on proton exchange membrane.Herein,we report a facile method to covert the biomass of black fungus into an efficient ORR catalyst.The black fungus undergoes hydrothermal and pyrolysis processes to transform into carbon-based materials.The as-obtained BF-N-950 catalyst shows prominent ORR catalytic activities in both acidic and alkaline electrolytes with a half-wave potential reaching 0.77 and 0.91 V,respectively.A membrane electrolyte assembly was fabricated with the as-obtained BF-N-950 as the cathode catalyst which shows a high peak power density of255 mW cm^-2.The study shows the potential of converting conventional biomass into low-cost ORR catalyst,which is promising for the fuel cell technology.

The dual role of hydrogen peroxide in fuel cells

Clean and highly efficient energy production has long been sought after, as a way to solve global energy and environmental problems. Fuel cells, which convert the chemical energy stored in fuel directly into electricity, are expected to be a key enabling technology for the pressing energy issues that plague our planet. Fuel cells require oxygen as an oxidant and require oxygen tank containers when used in air-free environments such as outer space and underwater. Hydrogen peroxide has been extensively uti- lized as an alternative liquid oxidant in place of gaseous oxygen. In addition to being an oxidant, hydrogen peroxide can donate electrons in the oxidation reaction to act as a fuel. This article provides an overview of the dual role of hydrogen peroxide in fuel-cell applications, including working principle, system design, and cell performance. Recent innovations and future perspectives of fuel cells that use hydrogen peroxide are particularly emphasized.