摘要：The efficient and selective electrocatalytic hydrogenation(ECH)of furfural is considered a green strategy for achieving biomass-derived high-value *** an aqueous electrolytic environment,a green hydrogen energy source of water,is significant for improving the selectivity of products and reducing energy *** this study,we systematically investigated the mechanism of pH dependence of product selectivity in the ECH of furfural on Cu *** acidic conditions,the oxygen atom dissociated directly from hydrogenated furfural-derived alkoxyl intermediates,followed by stepwise hydrogenation until H_(2)O formation via a thermodynamically favorable proton-coupled electron transfer process,thereby inducing a high proportion of the hydrogenolysis product(2-methylfuran).However,under partial alkaline conditions,furfural could be directly hydrogenated to furfuryl alcohol(selectivity~98%)due to the high-energy barrier of the deoxidation process via a surface hydride(Had)*** results highlight the vital role of the electrolytic environment in furfural selective conversion and broaden our fundamental understanding of hydrodeoxygenation reactions in ECH.

摘要：Better understanding of electrochemical reaction behaviors of hydrazine electrooxidation at metal phosphides has long been desired and the optimization of reaction kinetics has been proved to be ***,the dehydrogenation kinetics of hydrazine electrooxidation at Ni_(2)P is adjusted by Co as the(Ni_(0.6)Co_(0.4))_(2)P catalyzes HzOR effectively with onset potential of–45 mV and only 113 mV is needed to drive the current density of 50 mA cm^(‒2),showing over 60 mV lower than Ni_(2)P and Co_(2)*** also delivers the maximum power density of 263.0 mW cm^(-2) for direct hydrazine fuel *** experimental results revealed that Co doping not only decreases the adsorption energy of N_(2)H_(4) on Ni sites,lowering the energy barrier for dehydrogenation,but also acts as the active sites in the optimal reaction coordination to boost the reaction *** work represents a breakthrough in improving the catalytic performance of non‐precious metal electrocatalysts for hydrazine electrooxidation and highlights an energy‐saving electrochemical hydrogen production method.

摘要：将当前能源生产和消费结构从过度依赖化石能源转变为高效利用可再生能源,是解决能源危机、实现碳中和的有效途径。生物质是最有前途的可再生能源之一,可以取代化石燃料以获得有价值的有机化合物。近年来,大力利用生物质能已成为一种必然趋势。用于生物质转化的传统热化学催化方法通常需要高温、高压等恶劣条件,甚至还需要外部氢或氧源。相比之下,在相对温和的条件下进行的生物质有机分子电催化转化为生产高价值化学品提供了一种绿色高效的策略。特别是,通过C―C键裂解将生物质衍生的分子转化为高价值的短链化学品至关重要。近年来,大量的研究证明过渡金属(TM)电催化剂由于其丰富的三维电子结构和独特的eg轨道增强了过渡金属-氧之间的共价键合,从而在有机物的C―C键断裂中起着至关重要的作用。此外,TM电催化剂的配位环境或电子结构会影响产物的选择性。毫无疑问,明确的反应活性位点和途径有助于深入理解催化剂结构与反应活性之间的构效关系。然而,TM电催化剂介导的生物质衍生有机分子的C―C键裂解反应用于生物质升级的研究目前尚处于起步阶段,其反应机理和催化反应过程尚不清楚。因此,有必要在原子水平上系统地了解电催化剂在C―C键裂解过程中的作用。在本综述中,我们首先依次介绍了广泛研究的TM电催化剂介导的生物质衍生有机分子(包括甘油、环己醇、木质素和糠醛)的C―C键裂解反应,并给出了一些典型的例子和相应的反应途径。然后,系统回顾了过渡金属化合物催化C―C键裂解的反应机理,揭示了界面行为,并构建了TM电催化剂的结构与裂解反应活性之间的构效关系。最后,我们简要总结了上述内容,并强调了在TM电催化剂上研究C―C键裂解的挑战和展望。我们期望这项工作可以为生物质的可控转化和合理设计C―C键裂解的TM电催化剂提供指导。

摘要：Oxygen evolution reactions(OERs)as core components of energy conversion and storage technology systems,such as water splitting and rechargeable metal–air batteries,have attracted considerable attention in recent *** metal compounds,particularly layered double hydroxides(LDHs),are considered as the most promising electrocatalysts owing to their unique two-dimensional layer structures and tunable ***,heir poor intrinsic electrical conductivities and the limited number of active sites hinder their *** regulation of the electronic structure is an effective approach to improve the OER activity of LDHs,including cationic and anionic regulation,defect engineering,regulation of intercalated anions,and surface *** this review,we summarize recent advances in the regulation of the electronic structures of LDHs used as electrocatalysts in *** addition,we discuss the effects of each regulation type on OER *** review is expected to shed light on the development and design of effective OER electrocatalysts by summarizing various electronic structure regulation pathways and the effects on their catalytic performances.

摘要：High-temperature proton exchange membrane fuel cells(HT-PEMFCs)bring new opportunities for portable power generation due to their outstanding advantages such as high tolerance to fuel/air impurities and simplified heat/water ***,carbon-supported nanostructured Pt-based catalysts running at temperatures over 150℃are challenged by the severe aggregation and carbon corrosion,thus leading to poor ***,we demonstrate that dendritic Pt-Ni nanoparticles supported on fluorinated carbon black(white carbon black)could significantly enhance the performance and durability of HT-PEMFCs as the cathode catalysts running at 160℃due to the strong interaction of the F and Ni atoms to form a Ni_(x)F_(y) interface on Pt-Ni *** the formation of a stable Ni_(x)F_(y) interface,this integrated HT-PEMFC reached peak power densities of 906 mW cm^(−2) and demonstrated excellent durability at 160℃ under anhydrous H_(2)/O_(2) *** mitigation strategy was applied to Pt-alloy/C electrocatalysts and resulted in the elimination of Pt dissolution in practical fuel cells.

摘要：Electronic regulation of carbon is essential for developing non-platinum electrocatalysts for oxygen reduction reactions(ORRs).In this work,we used Cs to further regulate the electronic structure of nitrogen-doped(N-doped)*** Cs atoms coordinated with the nitrogen atom in the N-doped carbon for injecting electrons into the carbon conjugate structure and reducing the work function of the carbon *** low-work-function surface improved electron donation,facilitated O_(2) dissociation,and enhanced the adsorption of an OOH^(*) ***,electrocatalytic performance for the ORR was *** material shows potential as an ORR electrocatalyst comparable with Pt/C.

摘要：High-entropy alloys(HEAs)have been widely studied due to their unconventional compositions and unique physicochemical properties for various ***,for the first time,we propose a surface strain strategy to tune the electrocatalytic activity of HEAs for methanol oxidation reaction(MOR).High-resolution aberration-corrected scanning transmission electron microscopy(STEM)and elemental mapping demonstrate both uniform atomic dispersion and the formation of a face-centered cubic(FCC)crystalline structure in Pt Fe Co Ni Cu *** HEAs obtained by heat treatment at 700℃(HEA-700)exhibit 0.94%compressive strain compared with that obtained at 400℃(HEA-400).As expected,the specific activity and mass activity of HEA-700 is higher than that of HEA-400 and most of the state-of-the-art *** enhanced MOR activity can be attributed to a shorter Pt–Pt bond distance in HEA-700 resulting from compressive *** nonprecious metal atoms in the core could generate compressive strain and down shift d-band centers via electron transfer to surface Pt *** work presents a new perspective for the design of high-performance HEAs electrocatalysts.

摘要：作为一种可再生碳源,5-羟甲基糠醛(HMF)是一种重要的生物质平台分子,已被广泛用于制造医药前体、单体和精细化学品.HMF的电催化氧化反应(HMFOR)是一种在常温常压下实现HMF向2,5-呋喃二甲酸(FDCA)转化的高效绿色过程.但与传统的析氧反应(OER)不同,HMFOR相对复杂,需要经过6个电子的转移过程,分别涉及羟基和醛基的氧化.研究发现,NiO对羟基氧化具有较高的反应活性,但HMFOR反应途径受溶液pH值的影响,醛基以二元醇的形式优先在碱性溶液中被吸附和活化,从而导致反应活性较低.本文引入了导电聚合物聚吡咯(PPy),通过X射线光电子能谱(XPS)、原位红外光谱(FTIR)、高效液相色谱(HPLC)、密度泛函理论计算(DFT)、原位电化学石英晶体微天平(EQCM)等表征技术研究了PPy在引入NiO后对HMFOR的影响和催化性能差异的原因.X射线衍射结果表明,PPy引入的聚合过程没有破坏NiO的晶体结构,而FTIR显示出PPy分子中吡咯环的C-H弯曲振动及芳香胺分子中N-H的伸缩振动,说明PPy成功引入NiO表面.高分辨透射电镜结果表明,PPy以5 nm平均厚度薄层覆盖在NiO表面.此外,XPS结果证实了Ni,O,C和N元素的存在,吡咯氮(-NH-)物种在NiO-PPy电催化剂中占主导地位,而Ni 2p_(3/2)和O 1s的XPS谱中NiO和NiO-PPy且有相似的电子结构,说明PPy的引入并没有改变NiO的电子结构.线性扫描伏安曲线和电化学活性面积测试结果表明,PPy的引入显著提高了HMFOR的电流密度和NiO的内在活性.同时,NiO-PPy比NiO具有更低的Tafel斜率,表明PPy会提高HMFOR的反应动力学,加速HMF转化.电解测试中高效液相色谱分析结果表明,在前0.5 h内NiO-PPy催化剂上HMF转化率高于NiO催化剂,说明PPy的引入加速了HMF的转化.此外,分析中间产物发现,NiO催化剂上的HMFOR中间体主要为5-羟甲基呋喃-2-羧酸,而NiO-PPy上主要为2,5-二甲酰基呋喃.周期性测试结果表明,NiO-PPy表现出较高的HMF转化率和产物选择性,且具有较好的稳定性.运用开路电位和电化学石英晶体微天平检测了HMF分子在NiO和NiO-PPy上的吸附能力.结果表明,PPy涂层明显增强了HMF分子在NiO上的吸附能力.采用表面增强红外吸收光谱研究了电催化剂表面重要中间体的吸附行为.结果表明,NiO上HMFOR路径主要为HMFCA路径,而在NiO-PPy上新增2,5-二甲酰基呋喃,表明HMF分子的羟基和醛基同时在NiO-PPy表面被激活,进一步说明PPy的引入会选择性地提升羟基氧化的反应性能,进而提升了HMFOR活性.采用密度泛函理论研究了PPy的作用,结果表明正电性PPy分子会吸引电负性的羟基,缩短Ni与醛基之间的键长,降低醛基的反应活性,调节HMFOR反应途径,进而获得更高的HMFOR性能.综上所述,本文通过导电聚合物PPy修饰调控了电极界面微环境以及表面电性,从而调控了HMF分子的吸附构型和反应路径,获得更高的HMF电催化氧化反应活性.本文为HMF氧化高效电催化剂的设计提供了新的思路,并为HMF电催化氧化应用化研究提供借鉴.

摘要：氨是氮肥等工业的主要原料,因此氨产量居各种化工产品的首位.目前,90%以上的氨通过传统Haber-Bosch法制得,但该反应需要在高温高压下进行,消耗大量能源,同时排放大量CO_(2).基于此,科研人员致力于寻求一种绿色、高效的合成氨替代方法.其中,利用太阳能,通过光电化学氮还原合成氨是最有潜力和竞争力的方法之一,该方法也为有效利用太阳能提供了新途径.目前,虽然光电化学氮还原研究取得了一定进展,但是氨产率和氮转换效率低限制了其经济可行性.这主要归因于四个方面:(1)牢固的氮氮三键使得氮气难以活化;(2)复杂的多步和多电子反应使得动力学迟缓;(3)析氢竞争反应降低了太阳能-氨的转换效率;(4)氮气在水溶液中的溶解度低导致吸附在光电阴极表面的氮气较少.为解决上述问题,本文通过溅射法在B掺杂的p型(100)晶向硅片上共沉积Au,Co和Pd,然后在600℃下和空气中快速退火,制得由助催化剂/保护层/光吸收层组成的层级硅基光电阴极,并用于氮还原合成氨.成分和结构表征结果表明,层级硅基光电阴极由p型硅光吸收层、二氧化硅保护薄层和AuCoPd合金纳米颗粒助催化剂组成,该电极可表示为AuCoPd-CoOx/SiO_(2)/Si,简称ACP电阴极.角分辨X射线光电子能谱和同步辐射X射线吸收光谱结果表明,形成了局域电子结构AuCoPd合金纳米颗粒,并可分析出Au离子和Pd离子在纳米颗粒上的比例和分布.变压光电化学实验结果表明,ACP光电阴极表现出较好的氮还原合成氨性能,在3 MPa下氨产率达到22.2±0.4μg·h^(-1)·cm^(-2),法拉第效率达到22.9%.同时,ACP光电阴极的光电化学氮还原行为遵循勒夏特列(化学平衡移动)原理:随着反应压强增加,氨产率、法拉第效率和起始光电压均随之增大.原位X射线光电子能谱和原位同步辐射X射线吸收光谱结果表明,Au离子和Pd离子为氮还原反应的活性位点,为氮气活化及加氢提供反应场所;同时,揭示了邻近的Pd元素为Au物种上活化的氮气提供了活性质子,促进了氮还原合成氨反应进程.综上,本文为设计高效且稳定的光电阴极并应用于光电化学氮还原反应提供一定的参考.

摘要：生物质衍生物的电催化转化为可持续能源的增值利用提供了一条绿色高效的途径.例如,由5-羟甲基糠醛(HMF)氧化可得到生物基聚酯前驱体2,5-呋喃二甲酸(FDCA),对于缓解化石资源带来的能源危机和环境问题具有重要意义.目前,HMF的电催化氧化通常在强碱性(pH>13.5)溶液中进行,但是容易产生难以分离的腐殖质,影响FDCA的工业利用.另外,强碱性介质还存在腐蚀安全隐患、设备维护成本高等问题.中性反应条件有助于改善上述问题,但是缺乏亲电氧物种(例如OH-),HMF和催化剂的活化困难,难以得到高附加值产物FDCA.目前,针对中性介质中HMF的电催化氧化研究少有报道,急需明晰中性介质中HMF的催化机理,并开发中性条件下具有高活性的催化剂体系.本文利用均相催化剂2,2,6,6-四甲基哌啶-1-氧基(TEMPO)和Co_(3)O_(4)电极,对HMF进行中性条件下电催化氧化,1.55 VRHE条件下反应1.5 h,以接近100%转化率获得产物FDCA,产率大于99%.而在无TEMPO的条件下,HMF在Co_(3)O_(4)电极上转化率小于2%.原位红外等实验测试及理论计算结果表明,低电位(1.10 VRHE)下形成的TEMPO+阳离子的活化能显著减低HMF,通过脱氢作用选择性生成中间产物2,5-二甲酰基呋喃(DFF),对调控HMF的氧化路径、促进中性介质电催化氧化起到关键作用.原位X射线光电子能谱和电化学阻抗等结果发现,TEMPO存在时,1.35 V后,在含有高价态Co^(3+)/^(4+)的Co_(3)O_(4)电极上出现更多的水以及OH吸附物种,并导致HMF的氧化电流密度以及FDCA的转化率显著增加.理论计算结果表明,TEMPO自由基与水分子存在较强的氢键作用,有利于促进水活化提供OH.然而,低电位(1.25 V)以Co_(3)O_(4)为电极,或高电位(1.55 V)以泡沫镍为电极,即使添加TEMPO,电极上没有出现相应的OH吸附行为和电化学活性提升现象.因此,活性的Co_(3)O_(4)电极对于协同水的解离形成OH具有重要作用,二者共同作用下,水活化解离形成Co^(3+)/^(4+)-(OH)_(ads)活性中心.在中性溶液中,亲电氧物种OHads提供氧源,促进DFF等甲酰基中间体进一步氧化转化为FDCA.综上,本文加深了对中性介质中HMF的电催化氧化机制的理解,对设计类似电催化剂体系有借鉴作用.