利用石墨烯-炭黑组成的二元碳载体增强甲酸在钯催化剂上电化学氧化的活性（英文）

本文采用"一锅法"将氧化石墨烯(GO)、炭黑(C)和钯离子用NaBH4共还原,制备了石墨烯-炭黑二元载体(Gr-C)负载的钯催化剂(20%Pd/Gr-C),用于催化甲酸的电氧化反应.电化学测试结果表明,前驱体GO和C的质量比为3:7的Pd/Gr_(0.3)C_(0.7)催化剂催化活性最好,它的峰电流密度(102.14 mA mgPd~(-1))约为Pd/C催化剂(34.40 mA mgPd~(-1))的3倍,为钯/石墨烯催化剂(Pd/Gr,38.50 mA mgPd~(-1))的2.6倍.甲酸在Pd/Gr_(0.3)C_(0.7)催化剂电极直接氧化时的峰电位比Pd/C催化剂的峰电位负移约120mV,比Pd/Gr催化剂的峰电位负移约70 mV.采用透射电子显微镜(TEM)、扫描电子显微镜(SEM)、X射线衍射(XRD)、X射线光电子能谱(XPS)、拉曼光谱、电感耦合等离子发射光谱(ICP-AES)等手段对催化剂进行了表征.从SEM图像可以观察到,球形的炭黑团簇聚集在具有褶皱的石墨烯面上,形成了炭黑团簇/石墨烯三维立体结构,有效地抑制了相邻石墨烯层在范德华力作用下的吸引聚集和堆叠造成的石墨烯表面积减小,减小了单层石墨烯叠合成为多层石墨所造成的导电性损失,避免了相邻石墨烯片叠合形成封闭空间,有助于反应物和产物分子的运动.载体的三维结构使反应物分子更容易到达钯纳米粒子,有利于催化性能的提高.XPS结果也证实了二元Gr-C载体对Pd催化的促进作用.Pd/Gr_(0.3)C_(0.7)催化剂的Pd 3d5/2峰发生了右移,表明Pd 3d电子结合能正移,Pd 3d电子云密度降低.具有较低的3d电子云密度的Pd不易与甲酸氧化过程中吸附的中间体(COOH)ads结合,钯催化剂上(COOH)ads表面覆盖率降低,从而使甲酸更容易直接脱氢氧化生成CO_2,有利于甲酸通过直接途径进行电化学氧化.与Pd/C,Pd/Gr相比,Pd/Gr_(0.3)C_(0.7)催化剂对甲酸电氧化有最好的催化活性.Pd/Gr_(0.3)C_(0.7)催化剂优异的催化活性可归因于其内在的三维纳米结构:炭黑团簇有效地抑制了石墨烯纳米片的聚集,保持了其大的比表面积和高导电性,促进了反应物和产物分子的运动.此外,Pd纳米粒子与二元载体之间的强相互作用降低了Pd的3d电子云密度,使甲酸氧化主要经直接途径进行.本文证实了钯金属和石墨烯-炭黑二元载体之间的强相互作用,提供了简单和高性价比的方法以提高钯基催化剂的活性,有利于工业化的应用     

石墨烯的制备及石墨烯载Pd催化剂对甲酸的电催化氧化

以纳米石墨为原料,用两种方法分别制得石墨烯GN-1和GN-2。结果表明,用两种方法制备的石墨烯比表面积比纳米石墨都有显著增加。两种方法制备的石墨烯GN-1和GN-2形貌不同,孔径分布也有很大的差异。分别以两种方法制备的石墨烯为载体制备了Pd催化剂Pd/GN-1和Pd/GN-2。Pd/GN-1和Pd/GN-2催化剂的电化学比表面积分别为34.66和71.25 m2/g。这两种催化剂对甲酸的电催化氧化活性都较纳米石墨作载体制备的催化剂Pd/G有显著的提高,甲酸在Pd/GN-1和Pd/GN-2催化剂上的氧化峰电流密度分别为66.0和95.8 mA/cm2。两种催化剂对甲酸的氧化都有很好的稳定性。     

聚苯胺对钯催化甲酸电氧化反应的促进作用

钯基纳米材料是甲酸电氧化反应的优良催化剂.本工作制备了两个系列钯基催化剂,并考察了聚苯胺对钯上甲酸电氧化反应的助催化作用.一种是以聚苯胺为基底,在其表面电沉积钯纳米粒子,制得nPANI/Pd催化剂(n表示聚合苯胺的循环数);另一种是直接在商业Pd/C催化剂表面电聚合苯胺,制得Pd/C/nPANI催化剂.结果显示,聚苯胺单独存在时对甲酸电氧化反应没有催化活性,但其可对钯上甲酸电氧化反应呈现明显的促进作用,且促进作用与聚苯胺的厚度(聚合循环数)密切相关.在两个系列催化剂中,15PANI/Pd和Pd/C/20PANI显示出最高的催化性能.15PANI/Pd中钯的质量比催化活性是纯钯催化剂的7.5倍; Pd/C/20PANI中钯的质量比催化活性和本征催化活性分别是商业Pd/C催化剂的2.3和3.3倍.钯催化性能的提升与聚苯胺和钯纳米粒子间的电子效应有关.     

聚苯胺对钯催化甲酸电氧化反应的促进作用（英文）

钯基纳米材料是甲酸电氧化反应的优良催化剂.本工作制备了两个系列钯基催化剂,并考察了聚苯胺对钯上甲酸电氧化反应的助催化作用.一种是以聚苯胺为基底,在其表面电沉积钯纳米粒子,制得n PANI/Pd催化剂(n表示聚合苯胺的循环数);另一种是直接在商业Pd/C催化剂表面电聚合苯胺,制得Pd/C/n PANI催化剂.结果显示,聚苯胺单独存在时对甲酸电氧化反应没有催化活性,但其可对钯上甲酸电氧化反应呈现明显的促进作用,且促进作用与聚苯胺的厚度(聚合循环数)密切相关.在两个系列催化剂中,15PANI/Pd和Pd/C/20PANI显示出最高的催化性能.15PANI/Pd中钯的质量比催化活性是纯钯催化剂的7.5倍;Pd/C/20PANI中钯的质量比催化活性和本征催化活性分别是商业Pd/C催化剂的2.3和3.3倍.钯催化性能的提升与聚苯胺和钯纳米粒子间的电子效应有关.     

Pd/WO_3-RGO纳米催化剂对甲酸氧化的电催化性能

采用表面修饰技术将WO_3晶粒引入到氧化石墨烯(GO)表面,通过硼氢化钾还原法制备了载钯催化剂Pd/WO_3-RGO.对催化剂进行了结构和形貌表征,并考察了该催化剂对甲酸氧化的电催化性能.结果表明,Pd/WO_3-RGO催化剂由石墨烯、单斜态WO_3和立方面心Pd晶粒组成,Pd颗粒均匀分散在载体上;使用Pd/20%WO_3-RGO催化剂电极时的甲酸氧化最大峰电流密度大幅增加,是Pd/RGO催化剂电极甲酸氧化峰电流密度的2.5倍;Pd/WO_3-RGO催化剂稳定性大大增强,且具有更加优异的抗CO中毒能力;Pd晶粒与WO_3晶粒的相互交叠有利于它们之间的催化协同效应,增强催化剂的催化性能.     

复合碳载体负载Pd催化剂的乙醇电氧化性能

以石墨烯纳米片(GNP)和XC-72炭黑组成复合碳载体,制备了Pd/C-GNP催化剂,并考察了其乙醇电氧化性能.透射电子显微镜和X射线衍射分析结果表明,复合载体的采用改善了催化剂的结构,促进了Pd纳米粒子的分散.电化学测试结果表明,Pd/C-GNP催化剂具有较大的电化学活性表面积;在碱性介质中,Pd/C-GNP催化剂的乙醇氧化活性显著高于Pd/GNP和Pd/C催化剂;Pd/C-GNP催化剂还表现出优良的抗中毒能力,这可能得益于Pd/C-GNP催化剂中金属-载体的相互作用.     

Pd/石墨烯复合材料的制备及电催化甲酸和甲醇性能研究

通过电解高纯石墨棒的方法制备氧化石墨,将氧化石墨在超纯水中超声,形成稳定的氧化石墨烯分散液。以氧化石墨烯分散液和氯化钯作为前驱体,采用一步电沉积法制备Pd/石墨烯纳米复合材料。用扫描电子显微镜(SEM)、X射线衍射仪(XRD)及紫外可见分光光度计(UV-vis)对物质的表面形貌及物相组成进行表征分析。用循环伏安法(CV)和计时电流法(CA)研究了Pd/石墨烯催化剂对甲酸和甲醇的电催化氧化活性。结果表明:与纳米钯修饰电极相比,Pd/石墨烯修饰电极对甲酸及甲醇的电催化氧化活性有了极大的提高。     

Pd/TiC-C催化剂对甲酸氧化的电催化性能

研究了TiC和C作混合载体的Pd(Pd/TiC-C)催化剂对甲酸氧化的电催化性能。发现Pd/TiC-C催化剂对直接甲酸燃料电池(DFAFC)中甲酸氧化的电催化性能要优于Pd/C催化剂。而且,Pd/TiC-C催化剂的电催化性能与C和TiC的质量比有关,当质量比为2时,Pd/TiC-C催化剂对甲酸氧化的电催化活性和稳定性最好,甲酸在C和TiC的质量比为2的Pd/TiC-C催化剂电极上的氧化峰峰电位为0.164 V,比在Pd/C催化剂电极上负移12 mV,峰电流密度为23.08 mA/cm2,比在Pd/C催化剂电极上高约42％。     

碳化钨和Vulcan XC-72炭黑载钯催化剂对甲酸氧化的电催化性能

研究了碳化钨(WC)和Vulcan XC-72炭黑(XC)作混合载体的Pd/WC-XC催化剂对甲酸氧化的电催化性能.发现Pd/WC-XC催化剂对甲酸氧化的电催化性能优于Pd/XC催化剂.而且,Pd/WC-XC催化剂的电催化性能与WC和XC的质量比有关,当质量比为3:1时,催化剂对甲酸氧化的电催化活性最好,当质量比为2:1时,催化剂对甲酸氧化的电催化稳定性性最好.     

Pd/Fe_3O_4-C催化剂对甲醇、乙醇和丙醇氧化的电催化活性（英文）

制备对醇氧化反应具有优异电活性的钯催化剂是醇燃料电池研究的重要内容.本文用硼氢化钠还原法制备了钯纳米颗粒,然后沉积在Fe_3O_4/C复合物表面,得到了不同Fe_3O_4负载量的Pd/Fe_3O_4-C催化剂.透射电镜(TEM)检测显示,钯纳米颗粒均匀地分散在Fe_3O_4/C表面.对制备好的Pd/Fe_3O_4-C催化剂进行了循环伏安法(CV)、计时电流(CA)和电化学阻抗谱(EIS)的测试,研究了其在碱性介质中对C1-C3醇类(甲醇、乙醇和丙醇)氧化的电催化活性.结果表明,所制备的不同Fe_3O_4负载量的Pd/Fe_3O_4(2%)-C、Pd/Fe_3O_4(5%)-C、Pd/Fe_3O_4(10%)-C和Pd/C催化剂中,Pd/Fe_3O_4(5%)-C催化剂表现出最高的醇氧化电流密度.依据循环伏安(CV)数据,Pd/Fe_3O_4(5%)-C催化剂对甲醇、乙醇、正丙醇和异丙醇氧化的阳极峰电流密度分别是Pd/C催化剂的1.7、1.4、1.7和1.3倍.Pd/Fe_3O_4(5%)-C催化剂对乙醇氧化的电荷传递电阻也远低于Pd/C催化剂.制备的所有催化剂对C1-C3醇类电氧化的电流密度大小排序如下:正丙醇乙醇甲醇异丙醇.此外,碳粉中Fe_3O_4纳米颗粒的存在提高了钯纳米颗粒的电化学稳定性.     

An Efficient RuTe2/Graphene Catalyst for Electrochemical Hydrogen Evolution Reaction in Acid Electrolyte

Developing efficient powder catalysts for hydrogen evolution reaction (HER) in the acidic electrolyte is significant for hydrogen generation in the proton exchange membrane (PEM) water electrolysis technique. Herein, we demonstrated an efficient catalyst for HER in the acid media based on the graphene supported ruthenium telluride nanoparticles (RuTe₂/Gr). The catalysts were easily fabricated by a facile microwave irradiation/thermal annealing approach, and orthorhombic RuTe₂ crystals were found anchored over the graphene surface. The defective structure was demonstrated in the aberration‐corrected transmission electron microscopy images for RuTe₂ crystals and graphene support. This catalyst required an overpotential of 72 mV to drive 10 mA cm^?2 for HER when loading on the inert glass carbon electrode; Excellent catalytic stability in acidic media was also observed to offer 10 mA cm^?2 for 10 hours. The Volmer‐Tafel mechanism was indicated on RuTe₂/Gr catalyst by Tafel slope of 33 mV dec^?1, similar to that of Pt/C catalysts. The high catalytic performance of RuTe₂/Gr could be attributed to its high dispersion on the graphene surface, high electrical conductivity and low charge transfer resistance. This powder catalyst has potential application in the PEM water electrolysis technique because of its low cost and high stability.     

部分氧化碳化硅提高钯催化氧还原反应性能

燃料电池具有能量转换效率高的优点,是能量转换与储存的高效器件之一.目前,燃料电池阴极氧还原反应(ORR)动力学缓慢,并且催化ORR大量使用铂碳(Pt/C)催化剂,由于Pt储量少,价格高,载体碳材料易发生碳蚀导致催化剂稳定性降低,限制了其进一步商业化应用.钯(Pd)与Pt为同族元素,具有相似的电子结构和化学性质,其储量是...     

Nitrogen-doped carbon nanotube-encapsulated nickel nanoparticles assembled on graphene for efficient CO_2 electroreduction

Exploring 3 D hybrid nanocarbons encapsulated with metal nanoparticles(NPs) are recently considered as emerging catalysts for boosting CO_2 electroreduction reaction(CRR) under practical and economic limits.Herein,we report a one-step pyrolysis strategy for fabricating N-doped carbon nanotube(CNT)-encapsulated Ni NPs assembled on the surface of graphene(N/NiNPs@CNT/G) to efficiently convert CO_2 into CO.In such 3 D hybrid,the particle size of Ni NPs that coated by five graphitic carbon layers is less than 100 nm,and the amount of N dopants introduced into graphene with countable CNTs is determined to 7.27 at%.Thanks to unique CNT-encapsulated Ni NPs structure and N dopants,the achieved N/NiNPs@CNT/G hybrid displays an exceptional CRR activity with a high Faradaic efficiency of 97.7% and large CO partial current density of 7.9 mA/cm~2 at-0.7 V,which outperforms those reported metallic NPs loaded carbon based CRR electrocatalysts.Further,a low Tafel slope of 134 mV/dec,a turnover frequency of 387.3 CO/h at-0.9 V,and tiny performance losses during long-term CRR operation are observed on N/NiNPs@CNT/G.Experimental observations illustrate that the Ni NPs encapsulated by carbon layers along with N dopants are of great importance in the conversion of CO_2 into CO with high current density.     

非晶态NiP基催化剂的制备及电催化析氢性能研究

以NaH₂PO₂和Ni₂SO₄为磷源和镍源,使用一锅法合成了非晶态NiP合金及其碳纳米（乙炔黑和石墨烯）复合催化剂。用透射电子显微镜（TEM）、X射线衍射仪（XRD）、热重分析（TGA）、电感耦合等离子体光谱仪（ICP）分别对催化剂性能和组成进行了表征和分析。通过线性扫描伏安对催化剂在酸性和碱性条件下的析氢性能进行了评价,研究结果表明,非晶态NiP/还原氧化石墨烯复合催化剂（NiP/RGO）展现出优异的电催化性能。在0.5 mol/L H₂SO₄中的起始过电位为89.0 mV,塔菲尔斜率为135.1 mV/decade;在1 mol/L NaOH中,起始过电位为116.1 mV,塔菲尔斜率为122.4 mV/decade,这与商业化Pt黑催化剂很接近。500次循环以后,催化剂活性没有明显下降,表明该催化剂具有良好的稳定性。该研究提供了一种简单可行的制备非贵金属磷化物方法用于电催化析氢反应。     

One-step synthesis of carbon-supported Pd–Pt alloy electrocatalysts for methanol tolerant oxygen reduction

A facile, one-step reduction route was developed to synthesize Pd-rich carbon-supported Pd–Pt alloy electrocatalysts of different Pd/Pt atomic ratios. As-prepared Pd–Pt/C catalysts exhibit a single phase fcc structure and an expansion lattice parameter. Comparison of the oxygen reduction reaction (ORR) on the Pd–Pt/C alloy catalysts indicates that the Pd₃Pt₁/C bimetallic catalyst exhibits the highest ORR activity among all the Pd–Pt alloy catalysts and shows a comparative ORR activity with the commercial Pt/C catalyst. Moreover, all the Pd–Pt alloy catalysts exhibited much higher methanol tolerance during the ORR than the commercial Pt/C catalyst. High methanol tolerance of the Pd–Pt alloy catalysts could be attributed to the weak adsorption of methanol induced by the composition effect, to the presence of Pd atoms and to the formation of Pd-based alloys.     

负载无定型钌纳米簇的原子级钴掺杂一维碳纳米笼增强析氢催化性能

析氢反应是电解水产制氢的关键反应之一.在碱性条件下,由于催化剂表面与反应过程中产生的氧物种、氢物种与催化剂的吸附未处于最佳状态,析氢反应动力学往往比较缓慢,比在酸性条件下慢2-3个数量级.目前,铂基纳米催化剂被认为是最优的析氢催化剂,但因价格昂贵、稳定性较差,限制了其在电解水器件上的大规模应用.因此,设计一种价格较为低...     

Electrocatalytic oxidation of formic acid on functional MWCNTs supported nanostructured Pd–Au catalyst

In this work, PdAu nanocatalysts with different weight ratio of Pd and Au supported on functional multi-walled carbon nanotubes (f-MWCNTs) were prepared, and their electrocatalytic activity for the oxidation of formic acid was also studied. The electrocatalysts were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The electrochemical results showed that the 4Pd1Au/f-MWCNTs (by weight) catalyst, exhibited distinctly higher activity and better stability in formic acid electrooxidation than the Pd/f-MWCNTs catalyst. The Nano-Au improves potentially the performance of Pd-based electrocatalysts for the direct formic acid fuel cells (DFAFCs).     

Electrocatalytic activities of binary and ternary composite electrodes of Pd, nanocarbon and Ni for electro-oxidation of methanol in alkaline medium

Films of binary and ternary composites of Pd, nanocarbon (C), and Ni are obtained on glassy carbon electrodes and investigated as electrocatalysts for methanol oxidation (MOR) in alkaline medium. Results show that among the electrocatalysts investigated, the apparent electrocatalytic activity of the Pd-0.5%C electrode is the greatest and that it decreases with increasing percentage of C in the composite. The Pd-0.5%C composite electrode has approximately two times higher activity than that of Pd electrode for MOR under similar experimental conditions. Introduction of Ni (1–2%) into the active Pd-0.5%C catalyst somewhat declines the apparent electrocatalytic activity of the electrode. The onset potential for MOR is observed to be the greatest negative at the Pd-0.5%C composite electrode, which gets shifted towards noble side by 80–100 mV with addition of Ni (1–2%).     

A general bimetal-ion adsorption strategy to prepare nickel single atom catalysts anchored on graphene for efficient oxygen evolution reaction

Single-atom catalysts (SACs) supported on two-dimensional (2D) materials are highly attractive for maximizing their catalytic activity.However,graphene based SACs are primarily bonded with nitrogen and carbon sites,resulting in poor performance for the oxygen evolution reaction (OER).Herein,we develop a general bimetal-ion adsorption strategy for the synthesis of individually dispersed Ni SACs anchored on the oxygenated sites of ultrathin reduced graphene oxide as efficient OER electrocatalysts.The resultant Ni SACs for OER in alkaline electrolyte exhibit a highly stable overpotential of 328 mV at the current density of 10 mA cm~(-2),and Tafel slope of 84 mV dec~(-1) together with long-term durability and negligible degradation for 50 h,which is greatly outperform its counterparts of nitrogen bonded Ni SACs (564 mV,364 mV dec~(-1)) and Ni(OH)_2 nanoparticles anchored on graphene (450 mV,142 mV dec~(-1)),and most reported Ni based OER electrocatalysts.Furthermore,the extended X-ray absorption fine structure at the Ni K-edge and theoretical simulation reveal that the nickel-oxygen coordination significantly boost OER performance.Therefore,this work will open numerous opportunities for creating novel-type 2D SACs via oxygen-metal bonding as highly robust OER catalysts.     

碳纳米管负载的纳米Pd-Ag催化剂对乙醇和丙醇氧化的电化学活性

在乙二醇和水混合溶剂中,采用硼氢化钠还原的方法制备了多壁碳纳米管（MWCNT）负载的Pd和Pd-Ag纳米颗粒催化剂;在碱性介质中,用循环伏安法测试了这些催化剂对乙醇、正丙醇和异丙醇的电氧化性能。结果表明,Pd和Pd-Ag纳米颗粒均匀地分散在MWCNT表面;Pd/MWCNT、Pd₄Ag₁/MWCNT、Pd₂Ag₁/MWCNT和Pd₁Ag₁/MWCNT催化剂上金属颗粒的平均粒径分别为7、4、7和11 nm。相比乙醇和异丙醇,所制备的催化剂对正丙醇的氧化表现出较大的电流密度。与Pd/MWCNT催化剂相比,双金属Pd_nAg₁/MWCNT（n=4、2、1）催化剂,尤其是Pd₄Ag₁/MWCNT上的电流密度更大,表明Ag的加入提高了Pd催化剂对醇氧化的电化学活性,其原因是因为醇氧化过程所产生的中间体物种在双金属Pd-Ag/MWCNT催化剂上的吸附力有所减弱。