石墨烯量子点负载银纳米粒子制备及氧还原电催化活性

银基氧还原电催化剂具有较高的电催化活性且价格相对低廉,因而受到广泛关注. 本文采用简单、预先合成的石墨烯量子点作为载体和还原剂,制得了负载于石墨烯量子点、且无保护剂和表面活性剂的表面洁净银纳米粒子（Ag NPs/GQDs）. 电化学研究表明,Ag NPs/GQDs复合电催化剂的氧还原有较高的电催化活性,氧在碱性溶液中可经4电子途径还原为水. 与商业铂碳电极（Pt/C）相比,AgNPs/GQDs电极具有高催化电流密度、良好稳定性和极佳抗甲醇性能. 该银纳米粒子对开发高性能和低成本的非铂氧还原电催化剂有潜在的应用前景.     

微生物燃料电池非生物阴极催化剂的研究进展

在微生物燃料电池（MFC）中,以氧为电子受体具有很多优点,但氧阴极还原的反应动力学慢,会造成阴极电势的损失。 因此,提高阴极对氧还原的电催化活性和降低催化剂的价格是MFC非生物阴极催化剂的研究重点之一。 本文综述了近年来MFC中非生物阴极氧还原催化剂的研究进展。 重点讨论了贵金属Pt、过渡金属大环化合物以及金属氧化物催化剂对氧还原的电催化活性。 其中,非贵金属氧化物及过渡金属大环化合物催化剂具有良好的性能,而且价格低廉,有望成为MFC非生物阴极Pt基催化剂的替代催化剂。     

Pt 纳米颗粒在聚二甲基二烯丙基氯化铵功能化碳纳米管上的自发沉积及其对甲醇的电氧化性能

利用聚二甲基二烯丙基氯化铵(PDDA)非共价修饰的碳纳米管(CNTs)与PtCl₆^2-之间的自发氧化还原作用, 制备了Pt 纳米颗粒(Pt NPs)/CNTs-PDDA复合催化剂. PDDA在该催化剂中具有三种作用: (1) 作为金属前驱体PtCl₆^2-还原为Pt NPs 的还原剂; (2) 作为原位产生的Pt NPs 的稳定剂; (3) 在CNTs 表面形成保护膜抑制CNTs 在甲醇电催化氧化过程中的腐蚀. 采用傅里叶变换红外(FTIR)光谱、热重分析和拉曼光谱对CNTs-PDDA进行了表征, 表明PDDA通过π-π作用已成功覆盖在CNTs 表面, 并且修饰过程没有导致CNTs 结构的破坏. 采用透射电子显微镜(TEM)对Pt NPs/CNTs-PDDA 催化剂进行了表征, 结果表明, Pt NPs 均匀地分散在CNTs上, 平均粒径约2 nm, 且粒径分布范围窄. 用循环伏安法、计时电流法进一步考察了Pt NPs/CNTs-PDDA催化剂在酸性介质中对甲醇的电催化氧化的性能. 电化学测试结果表明, 与原始CNTs 负载的Pt NPs催化剂相比,Pt NPs/CNTs-PDDA催化剂具有更高的电化学活性表面积、电催化质量比活性和稳定性.     

P掺杂Pd3Fe1/C催化剂及其电催化氧还原活性

采用化学镀技术制备了P掺杂的Pd3Fe1/C,并考察了其对氧还原的电催化性能.结果表明,制得催化剂的Pd分散性高、粒径分布均匀;P的掺杂降低了Pd3Fe1/C催化剂的Pd-Fe颗粒粒径,提高了Pd3Fe1/C上氧还原的活性,且一定程度上改善了Pd3Fe1/C催化剂的稳定性.当Fe/P摩尔比为1/10时,催化剂的性能最佳...     

炭载Ru-Fe催化剂对直接甲酸燃料电池中氧还原的电催化性能研究

研究了作为直接甲酸燃料电池(DFAFC)阴极催化剂的炭载Ru(Ru/C)和炭载Ru-Fe(Ru-Fe/C)催化剂对氧还原的电催化性能和抗甲酸能力。发现Ru-Fe/C催化剂对氧还原的电催化活性要远好于Ru/C催化剂。进一步的研究发现,只有与Ru形成合金的Fe才能提高Ru/C催化剂对氧还原的电催化活性。另外,Ru-Fe/C催化剂对甲酸氧化没有电催化活性。因此,Ru-Fe/C催化剂也有很好的抗甲酸能力。所以,Ru-Fe/C催化剂适合作为DFAFC的阴极催化剂。     

碳载Pt-P催化剂对氧还原的电催化性能

用NaH2PO2液相还原方法制得碳载Pt-P(Pt-P/C)催化剂(m(Pt)∶m(P)=5∶1)。 X射线衍射谱测量表明,Pt-P/C催化剂的Pt衍射峰的2θ值稍大于Pt/C催化剂的相应值,表明P进入了Pt晶格,形成了Pt-P合金。 电化学测试表明,Pt-P/C催化剂对氧还原的电催化性能要比商品化的E-TEK Pt/C催化剂好,其还原电位正移了40 mV。 由于Pt-P/C催化剂中Pt-P粒子的平均粒径和相对结晶度与Pt/C催化剂相似,推测Pt-P/C催化剂对氧还原的电催化性能好于Pt/C催化剂的原因可能为P的作用。     

碳载Pt-P催化剂对氧还原的电催化性能

用NaH2PO2液相还原方法制得碳载Pt-P(Pt-P/C)催化剂(m(Pt)∶m(P)=5∶1)。 X射线衍射谱测量表明,Pt-P/C催化剂的Pt衍射峰的2θ值稍大于Pt/C催化剂的相应值,表明P进入了Pt晶格,形成了Pt-P合金。 电化学测试表明,Pt-P/C催化剂对氧还原的电催化性能要比商品化的E-TEK Pt/C催化剂好,其还原电位正移了40 mV。 由于Pt-P/C催化剂中Pt-P粒子的平均粒径和相对结晶度与Pt/C催化剂相似,推测Pt-P/C催化剂对氧还原的电催化性能好于Pt/C催化剂的原因可能为P的作用。     

硼、氮掺杂的二硫化钼用于氧还原电催化研究

对于碱性燃料电池的阴极反应,开发具有优异催化性能的新型催化剂至关重要.本工作采用一种简单的热解方法合成了硼、氮掺杂的二硫化钼(B,N-MoS2)材料并将其应用于氧还原(ORR)电催化分析.通过循环伏安法(CV)与线性扫描伏安法(LSV)等电化学分析方法,采用旋转盘电极(RDE)与旋转环盘电极(RRDE)等技术测试了该材...     

直接甲酸燃料电池用碳载铁卟啉-Au复合阴极催化剂的性能

研究了用于直接甲酸燃料电池(DFAFC)的碳载铁卟啉(FeTPP/C)、金复合阴极催化剂(FeTPP-Au/C)对氧还原的电催化性能和抗甲酸能力。结果表明,FeTPP-Au/C催化剂对氧气还原反应的电催化活性要远优于碳载铁卟啉(FeTPP/C)和碳载Au(Au/C)催化剂。而且,FeTPP-Au/C催化剂对甲酸氧化没有催化活性,因此,FeTPP-Au/C催化剂也有很好的抗甲酸能力。所以,FeTPP-Au/C催化剂适合作为DFAFC的阴极催化剂。     

直接甲醇燃料电池的Ir-Fe/C 阴极催化剂性能

合成了直接甲醇燃料电池的Ir-Fe/C阴极催化剂, 用X射线衍射(XRD)谱和X射线能量色散谱(EDS)等方法对该催化剂进行表征, 研究了碳载Ir-Fe(Ir-Fe/C)催化剂对氧还原的电催化活性和抗甲醇能力. 研究发现, 氧在碳载Ir(Ir/C)和Ir-Fe/C催化剂电极上还原的起始氧还原电位分别为0.57和0.65 V. 在0.2 V下的电流密度分别为4.6和5.8 mA/cm², 表明Ir-Fe/C催化剂对氧还原的电催化性能要优于Ir/C催化剂, 而且Ir-Fe/C催化剂也有很好的抗甲醇能力.     

银锡双金属催化剂的制备及其对氧还原的催化性能

在乙醇为溶剂和还原剂、碳粉为载体的体系中,采用水热法将Ag+或Ag+-Sn2+还原,形成纳米多孔网状结构的Ag或Ag-Sn双金属纳米颗粒,制备碳粉负载的Ag/C和Ag-Sn/C催化剂。 利用循环伏安和线性扫描技术,研究了碱性溶液中这些催化剂对氧还原反应(ORR)的电活性。 研究表明,Ag/C和Ag-Sn/C对ORR均表现出强的电催化活性,它们对ORR的起始电位约0.05 V（vs.Ag/AgCl）。 在Ag97Sn3/C催化剂上,ORR的电流密度为2.87×10-3 A/cm2(800 r/min),高于Ag/C。 Levich方程分析表明,在Ag-Sn/C催化剂上,ORR转移电子数明显大于Ag/C,说明在Ag-Sn/C催化剂上,氧气能够较为彻底被还原。 此外,在甲醇存在下,Ag/C和Ag-Sn/C对ORR的活性基本保持不变,表明它们对甲醇有较强的耐受力。     

Probing the Pt Surface for Oxygen Reduction by Insertion of Ag

We report on the probing of the Pt surface for oxygen reduction reaction (ORR) by insertion of Ag. Therefore, PtAg bimetallic nanoparticles were prepared by pulse electrodeposition. In a second step, Ag was electro‐dissolved in acidic media from the particles under formation of Pt skeleton. The ORR activity of these Pt skeleton depends on two factors: (1) on the surface properties of the Pt‐shell and (2) on the electronic as well as geometric influences of the remaining Ag in the particle core. By varying the conditioning procedure prior to measuring the ORR activity, we were able to differentiate between these two effects.     

Atomic ensemble and electronic effects in Ag-rich AgPd nanoalloy catalysts for oxygen reduction in alkaline media

The ability to design and characterize uniform, bimetallic alloy nanoparticles, where the less active metal enhances the activity of the more active metal, would be of broad interest in catalysis. Herein, we demonstrate that simultaneous reduction of Ag and Pd precursors provides uniform, Ag-rich AgPd alloy nanoparticles (~5 nm) with high activities for the oxygen reduction reaction (ORR) in alkaline media. The particles are crystalline and uniformly alloyed, as shown by X-ray diffraction and probe corrected scanning transmission electron microscopy. The ORR mass activity per total metal was 60% higher for the AgPd(2) alloy relative to pure Pd. The mass activities were 2.7 and 3.2 times higher for Ag(9)Pd (340 mA/mg(metal)) and Ag(4)Pd (598 mA/mg(metal)), respectively, than those expected for a linear combination of mass activities of Ag (60 mA/mg(Ag)) and Pd (799 mA/mg(Pd)) particles, based on rotating disk voltammetry. Moreover, these synergy factors reached 5-fold on a Pd mass basis. For silver-rich alloys (Ag(≥4)Pd), the particle surface is shown to contain single Pd atoms surrounded by Ag from cyclic voltammetry and CO stripping measurements. This morphology is favorable for the high activity through a combination of modified electronic structure, as shown by XPS, and ensemble effects, which facilitate the steps of oxygen bond breaking and desorption for the ORR. This concept of tuning the heteroatomic interactions on the surface of small nanoparticles with low concentrations of precious metals for high synergy in catalytic activity may be expected to be applicable to a wide variety of nanoalloys.     

Dealloyed Silver Nanoparticles as Efficient Catalyst Towards Oxygen Reduction in Alkaline Solution

Silver nanoparticles(Ag NPs) were prepared by dealloying Mg-Ag alloy precursor. The obtained Ag NPs have an average ligament size of (50±10) nm. Electrocatalytic activity of Ag NPs towards oxygen reduction reaction(ORR) in 0.1 mol/L NaOH solution was assessed via cyclic voltammetry(CV), rotating ring disk elec-trode(RRDE) techniques, and electrochemical impedance spectroscopy(EIS). The electrochemical active area for the ORR was evaluated by means of the charge of the underpotential deposition(UPD) of lead(Pb) on Ag NPs. The CV results indicate that Ag NPs have a higher current density and more positive onset potential than the bulk Ag electrode. RRDE was employed to determine kinetic parameters for O₂ reduction. Ag NPs exhibit a higher kinetic current density of 25.84 mA/cm² and a rate constant of 5.45×10^-2 cm/s at -0.35 V vs. Hg/HgO. The number of electrons(n) involved in ORR is close to 4. Further, EIS data show significantly low charge transfer resistances on the Ag NPs electrode. The results indicate that the prepared Ag NPs have a high activity and are promising catalyst for ORR in alkaline solution.     

Activation/Inhibition Effects during the Coelectrodeposition of PtAg Nanoparticles: Application for ORR in Alkaline Media

PtAg bimetallic nanoparticles for oxygen reduction reaction (ORR) in alkaline media were prepared by pulse electrodeposition (PED). During PED the reduction of Ag⁺ ions predominates, thus an increased Ag content in the co‐deposit is accomplished. The mechanism for this anomalous co‐deposition was elucidated by potential pulse experiments, which revealed that nuclei formation mainly occurs via the reduction of Pt²⁺ ions. The growth of the particles is diffusion controlled leading to the formation of a Ag shell covering a PtAg alloyed region. However, the shell is not growing homogeneously on the PtAg alloy. Hence, regions of the PtAg alloy are exposed, which exhibit an enhanced ORR activity compared to a pure Ag surface.     

Investigation of the electrocatalytic activity of boron-doped diamond electrodes modified with palladium or gold nanoparticles for oxygen reduction reaction in basic medium

The paper reports on the electrocatalytic activity of boron-doped diamond (BDD) electrodes electrochemically modified with palladium (Pd) or gold nanoparticles (Au NPs) towards oxygen reduction reaction (ORR) in alkaline medium. The BDD/Pd NP interface shows a well-defined diffusion-controlled voltammetric oxygen reduction peak at −0.25 V vs. Ag/AgCl. This is more positive than the ORR peak at −0.59 V vs. Ag/AgCl observed on BDD/Au-NP composite electrodes. The ORR proceeds via a four-electron process in both cases.     

Mono and bi-metallic electrocatalysts of Pt and Ag for oxygen reduction reaction synthesized by sonication

Nanoparticles of Ag, Pt and Pt–Ag were synthesized using ultrasonic irradiation with no consecutive thermal treatment to catalyze the oxygen reduction reaction. Metal nanoparticles are supported on carbon substrate. The synthesized materials were characterized by XRD, TEM, and cyclic and lineal voltammetry techniques. The kinetic formation of the metallic nanoparticles in solution was followed using UV–vis spectroscopy. The metal particles have crystalline structure and particle size with < 10 nm in size and in the form of spherical agglomerates. Ag/C exhibits lower electrochemical activity and stability for the ORR compared to Pt/C and Pt–Ag/C in acid medium. The mass and specific activity results demonstrate that the synthesized bimetallic sample exhibits 1.5 and 5 times greater electrochemical activities for the ORR compared to the commercial sample.     

NiO@rGO负载钯、银纳米粒子用作氧还原催化剂

为了促进燃料电池的广泛应用,必须研发一种高效、经济的氧还原（ORR）催化剂材料替代目前使用的昂贵的Pt基催化剂. 本文合成了NiO@rGO、Pd-NiO@rGO和Ag-NiO@rGO三种催化剂材料,并对其ORR催化性能进行了比较研究. 结果表明,三种材料均具有催化ORR的能力,但与NiO@rGO相比,Pd-NiO@rGO和Ag-NiO@rGO展示了更加优异的性能,主要表现在其4电子转移ORR过程、起始电位增加,中间产物的产率降低和稳定性提高. 其中,Pd-NiO@rGO作为ORR催化剂的性能最好.     

Oxygen reduction on electrodeposited silver catalysts in alkaline solution

In this study, silver was electrochemically deposited onto glassy carbon (GC) substrate using constant potential regime and tested for oxygen reduction reaction (ORR) in alkaline media. The surface morphology of Ag/GC electrodes was studied by scanning electron microscopy (SEM). It was established that after 10 s of deposition, a number of Ag nanoparticles with the size of 15 nm are produced that grow to about 45 nm after 300 s of electrodeposition. The ORR studies were conducted in 0.1 M KOH solution employing the rotating disk electrode (RDE) method. The Tafel slope at low current densities for electrodeposited silver is in the range from ?70 to ?80 mV. The RDE measurements showed that the electron transfer number (n) is 3.5 for smaller amounts of electrodeposited Ag, and it increases with increasing the loading of Ag on the GC surface. These n values suggest that the electroreduction of oxygen on Ag/GC electrodes proceeds mainly to water.     

ZIF-67衍生的Ag/Co@NC材料及其氧还原性能的研究

氮掺杂的多孔碳材料可作为氧还原反应的催化剂,本文借助ZIF-67富氮多孔的特殊结构,采用湿式逐步还原法将Ag嵌入ZIF-67孔腔内,然后在Ar中碳化成功地制备了Ag/Co双金属嵌入的氮掺杂的多孔碳复合材料（Ag/Co@NC）作为氧还原反应的催化剂. 为了证明Ag的突出作用,同时在Ar中碳化了ZIF-67制备了Co嵌入的氮掺杂的多孔碳材料（Co@NC）. 利用扫描电子显微镜、透射电子显微镜、X射线衍射、X射线光电子能谱以及比表面积分析对材料的显微形貌、物相组成、结构进行分析,采用循环伏安和线性扫描极化曲线对材料的氧还原催化活性和催化稳定性进行研究. 结果表明,Ag的嵌入未改变ZIF-67的晶体结构,但是大大提高了材料的氧还原催化活性. Ag/Co@NC材料的半波电位和起始电位均高于Co@NC材料,且其在1000次循环伏安测试前后的半波电位变化仅为30 mV,显示出很好的催化稳定性和甲醇耐受性,可作为燃料电池和金属-空气电池的阴极催化剂.