Acid Treated Carbon as Anodic Electrocatalysts toward Direct Ascorbic Acid Alkaline Membrane Fuel Cells

为改善电催化活性和亲水性，作者对商业碳黑（BP2000）进行了酸处理，获得了酸处理碳（ATC）. 通过X光电子能谱、红外光谱、热重和接触角测试的表征方法证明了酸处理在碳表面产生了丰富的含氧基团. 本文首次利用紫外可见光谱测试了碱性条件抗坏血酸（AA）在空气中的化学氧化活化能，结果为37.1 kJ·mol-1. 另外，利用交流阻抗谱对碱性条件下ATC作为电催化剂时AA的氧化反应的活化能进行了评价. 碱性条件下，AA在单电池中有无ATC电催化剂层条件下的活化能分别为26.5和34.5 kJ·mol-1，活化能的降低表明ATC是一种有效的阳极电催化剂. 作者将ATC应用于直接碱性膜AA燃料电池（DAAFCs）作为阳极电催化剂，并且对DAAFC中一系列参数进行了优化，包括催化剂在膜（CCM）或气体扩散层（CDM）上的喷涂方法、阳极电催化剂的载量、阳极电催化剂中碱性聚合物的比例. 结果表明，采用CCM的膜电极制备方法、0.5 mg·cm-2的ATC载量、25wt%的碱性聚合物添加比例时，DAAFCs单池的功率密度可达18.5 mW·cm-2，远高于使用商品PtRu/C（5 mW·cm-2）做阳极电催化剂的单池. 在寿命测试中，使用溶解于1 mol·L-1 NaOH水溶液中的 0.5 mol·L-1 AA作为燃料（流速15 mL·min-1），DAAFCs单池的功率密度可以在25 min内维持在4 mW·cm-2以上（75 °C）.In order to improve the hydrophilicity and electrocatalytic activity, commercial carbon black (BP 2000) was subjected to acid treatment to obtain acid-treated carbon (ATC). The generation of rich oxygen-containing groups on the surface of the ATC was proved by X-ray photoelectron spectra (XPS), Fourier transform-infra red spectra (FTIR), thermogravimetric analysis (TG) and contact angle measurement. UV-vis spectra were firstly recorded to calculate activation energy (Ea) of ascorbic acid (AA) chemical oxidation in alkaline conditions by oxygen in air and the Ea value was determined to be 37.1 kJ·mol-1. Additionally, electrochemical impedance spectra (EIS) were used to evaluate unprecedented Eaelectrochem of ATC as electrocatalysts toward ascorbic acid (AA) oxidation in alkaline media. The Eaelectrochem values of electrochemical oxidation in alkaline membrane electrode assembly (MEA) setup of a single cell without and with ATC as the anodic electrocatalysts were calculated to be 34.5 and 26.5 kJ·mol-1, respectively. The diminished Eaelectrochem suggests that ATC does function as an effective anodic electrocatalyst. Furthermore, the ATC was applied in direct ascorbic acid alkaline membrane fuel cell (DAAFC) for the first time. We optimized a series of parameters for the fabrication of MEAs including catalyst coated membrane (CCM) or catalyst coated gas diffusion layer membrane (CDM), loading of anodic electrocatalyst, and ionomer content in the electrocatalyst slurry. It turned out that the CCM with the ATC loading of 0.5 mg·cm-2 and 25wt% ionomer reached a high power density of 18.5 mW·cm-2, which is higher than that of using PtRu/C as anodic electrocatalyst (less than 5.0 mW·cm-2). In addition, the DAAFC fed with 15 mL·min-1 of the fuel containing 0.5 mol·L-1 AA and 1 mol·L-1 NaOH aq. could stably hold a power density at 4 mW·cm-2 for 25 min.国家自然科学基金（No.21003114, No.21103163, No.21306188, No.21373211, No. 21306187），国家重点专项（No.2016YFB0101307），辽宁百千万人才计划（No.201519），辽宁省高等学校优秀科技人才支持计划（No.LR201514）， 大连市优秀青年科技人才（No.2015R006）资助.This study was supported by National Key Research & Development Program of China (Gran No. 2016YFB0101307), National Natural Science Fund of China (Grant Nos. 21003114, 21103163, 21306188, 21373211, and 21306187), Liaoning BaiQianWan Talents Program (Grant No. 201519), Program for Liaoning Excellent Talents in University (Grant No. LR201514), Dalian Excellent Young Scientific and Technological Talents (Grant No. 2015R006)　　作者联系地址：1.大连理工大学，精细化工国家重点实验室&电化学工程实验室，化工学院，辽宁 大连，116024；2. 中国科学院大连化物所，辽宁 大连，116023Author's Address: 1. State Key Laboratory of Fine Chemicals, School of Chemical Engineering, Dalian University of Technology, Dalian 116024, China; 2. Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China通讯作者E-mail：[email protected]

Core-Shell Structured Ru@PtRu Nanoflower Electrocatalysts toward Alkaline Hydrogen Evolution Reaction

本文通过分步还原Ru、Pt前驱体,制备了以Ru为核、PtRu合金为壳的[email protected]纳米花电催化剂,其平均直径为16.5±4.0 nm. 利用高分辨电子显微镜、电感耦合等离子体原子发射光谱和X射线光电子能谱等表征了这种电催化剂的结构和组成. 在1 mol·L -1 KOH水溶液中,核壳结构[email protected]/C纳米花氢析出反应的过电位为22 mV（@10 mA·cm -2）,耐久性测试后过电位增加至30 mV（@10 mA·cm -2）,明显优于商业Pt/C电催化剂（初始值：60 mV@10 mA·cm -2,耐久性测试后：85 mV@10mA·cm -2）. 显著提高的电化学活性可能源于核壳结构[email protected]纳米花的电子效应和几何效应,耐久性的改善可能源于核壳结构[email protected]纳米花结构的稳定性.Water electrolysis for hydrogen production is beneficial for solving the problem of energy crisis and environmental issues. It is necessary to study highly active and cost-effective catalysts toward hydrogen evolution reaction (HER) to reduce the consumption of noble metals. Herein, we report the synthesis of core-shell structured [email protected] nanoflowers electrocatalyst by stepwise reduction of Ru and Pt precursors in the mixture of oleylamine and benzyl alcohol at 160 oC. The average diameter of the resultant [email protected] was 16.5±4.0 nm with a bulk atomic ratio between Pt and Ru of 0.24:1 and a surface ratio of 3.3:1 between Pt and Ru. Therefore, we speculate the formation of core-shell structure with Ru as the core and PtRu alloy as the shell. The performance of the electrocatalyst toward alkaline HER was tested in 1.0 mol·L -1 KOH aqueous solution. The [email protected] exhibited pronounced alkaline HER activity with a small overpotential of 22 mV at 10 mA·cm -2, a low Tafel slope of 43 mV·dec -1, and a high mass activity of 5.68 A·mg -1Pt+Ru at an overpotential of 100 mV, all largely surpassing commercial Pt/C (60 mV, 101 mV·dec -1, 1.53 A·mg -1Pt). The attained [email protected] also held outstanding long-term cycling stability. After 10,000 potential cycles from 0.1 to -0.1 V (vs. RHE), the overpotential increased to 30 mV at 10 mA·cm -2, while increased to 85 mV for Pt/C. The significantly improved electrochemical activity may be derived from the electronic and geometric effects of the electrocatalyst. The improvement of durability may be due to the stability of the flower-like dendritic morphology.国家重点研发计划课题No(2019YFB1504501);大连理工大学重点专项No(DUT19ZD208);大连理工大学重点专项No(DUT20ZD208);中央引导地方专项No(2020JH6/10500021);辽宁省重点研发计划项目No(2020JH2/10100025);大连市重点学科重大项目资助No(2020JJ25CY003)通讯作者:宋玉江E-mail:[email protected]:SONGYu-jiangE-mail:[email protected]大连理工大学化工学院精细化工国家重点实验室,辽宁 大连 116024State Key Laboratory of Fine Chemicals, School of Chemical Engineering,Dalian University of Technology, Dalian 116024, Liaoning, Chin