Vertical copper oxide nanowire arrays attached three-dimensional macroporous framework as a self-supported sensor for sensitive hydrogen peroxide detection

A hierarchical nanostructure consisting of uniform copper oxide nanowires vertically grown on three-dimensional copper framework (CuO NWs/3D-Cu foam) was prepared by a two-step synthetic process. The uniform CuO NWs anchored onto the 3D foam exhibited outstanding electrocatalytic activity towards hydrogen peroxide reduction due to the unique one‐dimensional direction with its excellent catalytic activity and large surface area of 3D substrate, which enhanced electroactive sites and charge conductivity. As a result, a wide linear detection range of 1 µM–1 mM, good sensitivity of 8.87 µA/(mM ⋅ cm²), low detection limit of 0.98 µM, and rapid response time of 5 s to hydrogen peroxide were achieved under a working potential of −0.4 V in phosphate buffer solution (pH of 7.4). In addition, the CuO NWs/3D-Cu foam material showed excellent selectivity to hydrogen peroxide and good resistance against poisonous interferents, including ascorbic acid, dopamine, urea, uric acid, and potassium chloride. Furthermore, the CuO NWs/3D-Cu foam presented good reproducibility, stability, and accurate detection for hydrogen peroxide in real sample; therefore, it may be considered to be a potential free-standing hydrogen peroxide sensor in practical analysis applications.     

Electrochemically Co‐deposited Teeth‐like Virus‐Platinum Nanohybrids as an Electrocatalyst for Methanol Oxidation Reaction

M13 virus (M13) as scaffolds has a major appeal, owing to their mono‐dispersed, fibrillar morphology and engineerable surface reactive sites. Herein we had developed a facile electrocatalyst for energy application. Platinum nanostructures are directly co‐deposited from a wild‐type M13 (or) two different engineered M13 mixed electrolytes onto the ITO electrodes. The engineered M13 with 4E peptides could specifically nucleate Pt precursor thereby enables the efficient growth of teeth‐like structures at the ITO electrode. The electrocatalytic activity of the resulting electrocatalyst toward methanol oxidation in alkaline medium was investigated and found enhanced mass activity (0.321 A/mg_Pt) relative to the catalyst prepared from wild‐type M13, Y3E peptides engineered M13 and without M13. Our novel electrocatalyst fabrication can be extended to other metal and metal oxides and its application might be useful to develop novel clean and green energy generating and storage materials.     

Dynamically Restructuring NixCryO Electrocatalyst for Stable Oxygen Evolution Reaction in Real Seawater

In the pursuit of long-term stability for oxygen evolution reaction (OER) in seawater, retaining the intrinsic catalytic activity is essential but has remained challenging. Herein, we developed a Ni_xCr_yO electrocatalyst that manifested exceptional OER stability in alkaline condition while improving the activity over time by dynamic self-restructuring. In 1 M KOH, Ni_xCr_yO required overpotentials of only 270 and 320 mV to achieve current densities of 100 and 500 mA cm⁻², respectively, with excellent long-term stability exceeding 475 h at 100 mA cm⁻² and 280 h at 500 mA cm⁻². The combination of electrochemical measurements and in situ studies revealed that leaching and redistribution of Cr during the prolonged electrolysis resulted in increased electrochemically active surface area. This eventually enhanced the catalyst porosity and improved OER activity. Ni_xCr_yO was further applied in real seawater from the Red Sea (without purification, 1 M KOH added), envisaging that the dynamically evolving porosity can offset the adverse active site-blocking effect posed by the seawater impurities. Remarkably, Ni_xCr_yO exhibited stable operation for 2000, 275 and 100 h in seawater at 10, 100 and 500 mA cm⁻², respectively. The proposed catalyst and the mechanistic insights represented a step towards realization of non-noble metal-based direct seawater splitting.     

Electron-Donors–Acceptors Interaction Enhancing Electrocatalytic Activity of Metal-Organic Polymers for Oxygen Reduction

Catalysts with metal-N_x sites have long been considered as effective electrocatalysts for oxygen reduction reaction (ORR), yet the accurate structure-property correlations of these active sites remain debatable. Report here is a proof-of-concept method to construct 1,4,8,11-tetraaza[14]annulene (TAA)-based polymer nanocomposites with well-managed electronic microenvironment via electron-donors/acceptors interaction of altering electron-withdrawing β-site substituents. DFT calculation proves the optimal −Cl substituted catalyst (CoTAA−Cl@GR) tailored the key OH* intermediate interaction with Co−N₄ sites under the d-orbital regulation, hence reaching the top of ORR performance with excellent turnover frequency (0.49 e s⁻¹ site⁻¹). The combination of in situ scanning electrochemical microscopy and variable-frequency square wave voltammetry techniques contribute the great ORR kinetics of CoTAA−Cl@GR to the relatively high accessible site density (7.71×10¹⁹ site g⁻¹) and fast electron outbound propagation mechanism. This work provides theoretical guidance for rational design of high-performance catalysts for ORR and beyond.     

Multi-component electrocatalyst for low-temperature fuel cells synthesized via sonochemical reactions

This review presents recent advances in multi-component electrocatalysts for low-temperature fuel cells (FCs) synthesized via sonochemical reactions. As a feasible approach to develop novel electrocatalysts that can overcome the many problems of the prevailing Pt electrocatalysts, Pt- or Pd-based alloy and core–shell M@Pt nanoparticles (NPs) have been pursued. Synthesizing NPs with desirable properties often turn out to be challenging. Sonochemistry generates extreme conditions via acoustic cavitation, which have been utilized in the syntheses of various Pt and Pd NPs and Pt- and Pd-based alloy NPs. Especially, it has been reported that several M@Pt core–shell NPs can be synthesized by sonochemistry, which is hard to achieve by other methods. The principles of sonochemistry are presented with examples. Also alloy NPs and core–shell NPs synthesized by sonochemistry and those by other methods are compared.     

Accelerating electrochemistry with metal nanowires

Scalable, solution-phase syntheses of metal nanowires are enabling their increased use in electrochemical processes. This review highlights recent results demonstrating how metal nanowires can exhibit better durability and higher activity than traditional metal nanoparticle electrocatalysts on carbon supports. Metal nanowires can also form interconnected two-dimensional and three-dimensional (3D) networks that eliminate the need for a carbon support, thus eliminating the detrimental effects of carbon corrosion. Porous 3D networks of nanowires can be used as flow-through electrodes with the highest specific surface areas and mass transport coefficients obtained to date, enabling dramatic increases in the productivity of electrochemical reactions. Nanowire networks are also serving as 3D current collectors that improve the capacity of batteries. The tunable surface structure and dimensions of metal nanowires offer researchers a new opportunity to create electrodes that are tailored from the atomic scale to the microscale to improve electrochemical performance.     

Graphene Supported Platinum Nanoparticles as Catalyst for Oxygen Reduction Reaction

Graphene supported Pt nanoparticles were fabricated via electrochemical reduction method and the application of them in oxygen reduction reaction was also investigated. The results of field emission scanning electron microscope(SEM), X-ray photoelectron spectroscopy(XPS) and Raman spectroscopy reveal that the interaction between Pt nanoparticles and graphene sheets can prevent graphene from agglomeration and improve the electronic conductivity of the composite. And the graphene supported Pt nanoparticles exhibit excellent electrocatalytic activity toward oxygen reduction reaction.     

Platinum–tin complexes as catalysts for the anodic oxidation of borohydride

Platinum–tin complexes were prepared by the reduction of Pt(IV) with Sn(II) in HCl media and studied by light absorption spectrometry, X-ray photoelectron spectroscopy (XPS), and electron microscopy. The formation of three complexes, H₃[Pt(SnCl₃)₅], H₂[Pt(SnCl₃)₂Cl₂], and H₂[Pt₃(SnCl₃)₈], depending on HCl and SnCl₂ concentrations, has been shown. The glassy carbon (GC) electrode modified in the complexes solutions was found to be an electrocatalyst for borohydride oxidation in a 1.0-M NaOH solution. Comparison of BH₄ ⁻ electrooxidation on Pt and on GC modified with platinum–tin complexes has shown that catalytic hydrolysis of BH₄ ⁻ did not proceed in the latter case in contrast to its oxidation on the Pt electrode, and only direct BH₄ ⁻ oxidation has been observed in the positive potentials scan. The activity of Pt–Sn complexes for BH₄ ⁻ oxidation changes with time and eventually decreases due to Sn(II), bound in the complex with Pt(II), oxidation by atmospheric oxygen. The complexes may be renewed by addition of missing amounts of SnCl₂ and HCl.     

制备条件对甲醇电氧化催化剂PtRu/CAs性能的影响

本文利用液相浸渍还原的方法制备了PtRu/C催化剂, 其中Pt质量百分含量分别为15%, Pt和Ru的原子比为2:1. 研究了金属前驱体于不同介质（CH3COOH、H2O及CH3COONa）中浸渍所制备的催化剂组成, 结构以及活性方面的区别. 同时比较分析了不同载体（碳纳米管CNTs与碳气凝胶CAs）对催化剂性能的影响. 催化剂的物化性质通过XRD, TEM以及EDS来表征, 并采用循环伏安法测试其电化学性能. 结果表明以碳气凝胶为载体,均匀分散于异丙醇与水混合溶液后, 加入CH3COOH, 使金属前驱体在酸性介质中浸渍, 再用NaOH调节pH值至碱性, 同时生成CH3COONa作为稳定剂, 然后再用NaBH4还原所制得的催化剂具有更高的电催化活性, 其峰电流密度达到38.24 mA/cm2, 远高于本文中在其他条件下制备的催化剂.     

Pd/Fe3O4-C催化剂对甲醇、乙醇和丙醇氧化的电催化活性

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Fe3O4/C复合物表面, 得到了不同Fe₃O₄负载量的Pd/Fe₃O₄-C催化剂. 透射电镜（TEM）图显示钯纳米颗粒均匀地分散在Fe₃O₄/C表面. 对制备好的Pd/Fe₃O₄-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Fe₃O₄负载量的Pd/Fe₃O₄(2%)-C,Pd/Fe₃O₄(5%)-C, Pd/Fe₃O₄(10%)-C和Pd/C催化剂中, Pd/Fe₃O₄(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/Fe₃O₄(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/Fe₃O₄(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Fe₃O₄纳米颗粒的存在提高了钯纳米颗粒的电化学稳定性.