Role of Bridge-bonded Formate in Formic Acid Dehydration to CO at Pt Electrode： Electrochemial in-situ Infrared Spectroscopic Study

Formic acid （HCOOH） decomposition at Pt film electrode has been studied by electrochem- ical in situ FTIR spectroscopy under attenuated-total-reflection configuration, in order to clarify whether bridge-bonded formate （HCOOD） is the reactive intermediate for COad for-mation from HCOOH molecules. When switching from HCOOH-free solution to HCOOH- containing solution at constant potential （E=0.4 V vs. RHE）, we found that immediately upon solution switch COad formation rate is the highest, while surface coverage of formate is zero, then after COad formation rate decreases, while formate coverage reaches a steady state coverage quickly within ca. 1 s. Potential step experiment from E=0.75 V to 0.35 V, reveals that formate band intensity drops immediately right after the potential step, while the COad signal develops slowly with time. Both facts indicate that formate is not the reactive intermediate for formic acid dehydration to CO.

A Revisit to the Role of Bridge-adsorbed Formate in the Electrocatalytic Oxidation of Formic Acid at Pt Electrodes

The mechanism and kinetics of electrocatalytic oxidation of formic acid at Pt electrodes is discussed in detail based on previous electrochemical in-situ ATR-FTIRS data [Langmuir 22, 10399 （2006）and Angewa. Chem. Int. Ed. 50, 1159 （2011）]. A kinetic model with formic acid adsorption （and probably the simultaneous C-H bond activation） as the rate determining step, which contributes to the majority of reaction current for formic acid oxi- dation, was proposed for the direct pathway. The model simulates well the IR spectroscopic results obtained under conditions where the poisoning effect of carbon monoxide （CO） is negligible and formic acid concentration is below 0.1 mol/L. The kinetic simulation predicts that in the direct pathway formic acid oxidation probably only needs one Pt atom as active site, formate is the site blocking species instead of being the active intermediate. We review in detail the conclusion that formate pathway （with either 1st or 2nd order reaction kinetics） is the direct pathway, possible origins for the discrepancies are pointed out.

Determination of Isotherm for Acetate and Formate Adsorption at Pt（111） Electrode by Fast Scan Voltammetry

Fast scan voltammetry is an efficient tool to distinguish oxidative/reductive adsorp- tion/desorption from that for bulk reaction. In this work, we provide a methodology that the isotherm of oxidative/reductive adsorption desorption processes at electrode surface can be obtained using just one solution with relatively low reactant concentration, by taking the advantage of varying the potential scan rate （relative of the diffusion rate） to tune the adsorption rate and proper mathematic treatment. The methodology is demonstrated by taking acetate adsorption at Pt（lll） in acidic solution as an example. The possibility for extension of this method toward mechanistic studies of complicated electrocatalytic reactions is also given.

质子交换膜测试方法国家标准解读

本文重点介绍GB/T 20042.3-2022《质子交换膜燃料电池第3部分:质子交换膜测试方法》中质子交换膜的主要测试项目和测试方法,通过与原标准的比较,进一步解读该新版标准中测试方法的技术改进和变化内容,并为氢能产业标准化的实施提出建议。

燃料电池质子膜氢气透过率测定方法

随着氢能经济时代的来临,燃料电池的商业化应用受到越来越多的关注.作为燃料电池内部的核心部件,质子膜的氢气透过率是影响膜电极性能的关键因素之一.通过对现有的氢气透过率测试方法从测试装置和测试条件方面进行改进,实现了氢气透过率测试的在线监测,不仅提高了现有检测结果的准确性,而且还提升了测试效率.

初中数学教学中合作学习的尝试

长期以来，传统数学教学过程中是以知识传授为主，而忽视了学习方法的指导。《数学课程标准》大力倡导一种“动手实践，自主探索，合作交流的学习方式”。那么，教师作为数学学习的组织者、引导者与合作者，必须适应课程改革的要求，转变自身的教学方式。应该立足于培养学生的合作意识，引导学生开展合作学习。

在数学教学中培养学生的反思意识

通过在课堂教学、解题训练和学生自主学习中培养学生的反思意识，可以使学生深化对问题的理解，优化思维过程，完善认知结构，提高学生的数学综合素养。

燃料电池膜用全氟磺酸树脂溶液中铁含量的测定

近年来,燃料电池汽车受到越来越多的关注,而燃料电池汽车的商业化还有很多问题亟需解决。燃料电池膜作为燃料电池的核心部分,在制膜前需要检测所用全氟磺酸树脂溶液中的铁离子含量,铁离子含量直接影响燃料电池膜的化学性能。全氟磺酸树脂溶液是一种高分子溶液,存在多分散和不稳定性。采用高分子待测溶液用水-丙醇稀释后作为空白样品,并用丙醇溶液作为定容液,在用邻菲啰啉显色后,采用紫外吸光光度法测定铁离子含量。测定结果分析误差在5%以内,准确性和重现性满足试验要求。

温度—应力耦合下质子交换膜拉伸蠕变行为及本构描述

质子交换膜作为质子交换膜电池核心部件,其蠕变性能对质子交换膜电池的结构设计至关重要。通过研究质子交换膜在不同温度、应力下的拉伸蠕变性能,探究应力、温度对质子交换膜短期蠕变行为的耦合影响规律。分别采用Burgers模型和Findley幂律模型对质子交换膜短期蠕变行为进行拟合,分析了Burgers模型和Findley幂律模型的相关系数及变化规律。结果表明,在不同的温度、应力水平下,质子交换膜蠕变曲线均包含瞬态蠕变阶段和稳态蠕变阶段,瞬间弹性形变、延迟弹性形变和黏性流动形变均表现出对温度、应力的依赖性;Burgers模型和Findley幂律模型都能很好地模拟质子交换膜的蠕变性能。最后,通过稳态蠕变速率与温度、应力水平的量化关系获得了应力指数和蠕变激活能,分析了质子交换膜的蠕变行为与机理。