泡沫镍载 NiCO2O4电极的制备及其催化 H2O2电氧化的性能

本文以水热法结合热处理法原位制备了泡沫镍载 NiCo₂O₄纳米线电极,使用XRD、SEM和TEM对合成的 NiCo₂O₄纳米线进行了表征,NiCo₂O₄纳米线直径约80 nm,长度约 3 ~ 5 μm. 使用循环伏安和计时电流法测试了泡沫镍载NiCo₂O₄纳米线催化H₂O₂的电氧化性能,结果表明泡沫镍载NiCo₂O₄纳米线对H₂O₂电氧化有着优良的催化活性、稳定性和传质性能,在0.3 V电位下0.4 mol·L ^-1 H₂O₂和2 mol·L ^-1 NaOH溶液中氧化电流可达380 mA·cm ^-2.     

还原氧化石墨烯修饰泡沫镍原位负载MnO2对H2O2电还原反应催化性能的研究

采用两步易操作的水热法制备了还原氧化石墨烯（rGO）修饰泡沫镍（Ni foam）基体原位负载MnO₂纳米片（MnO₂/rGO@Ni foam）催化剂电极.通过X射线衍射（XRD）、扫描电子显微镜（SEM）、透射电子显微镜（TEM）对电极的微观形貌和组成进行了表征.利用循环伏安法和计时电流法对电极对H₂O₂电还原反应的催化性能进行了系统的测试.根据测试结果得知,电极在3 mol/L NaOH和1 mol/L H₂O₂溶液中表现出最佳的催化性能.在该溶液中,当电位为－0.8V时,H₂O₂电还原反应的电流密度可以达到240 mA/cm²,高于同等条件下MnO₂直接生长在Ni foam上的电流密度180mA/cm².通过不同温度下的极化曲线计算出了在该电极上H₂O₂电还原反应所需的活化能大小为21.53 kJ/mol,明显低于文献中报道的数值.对比实验结果表明rGO的加入显著地改善了MnO₂催化剂的催化性能与稳定性.     

还原氧化石墨烯/TiO2纳米复合物制备及其光催化性能

采用一步水热法制备了还原氧化石墨烯-二氧化钛(RGO-P25)纳米复合物.通过透射电子显微镜(TEM)、傅里叶变换红外(FTIR)光谱、X射线光电子能谱(XPS)、X射线衍射(XRD)及紫外-可见漫反射谱(UVVisDRS)对复合材料的结构和光电性能进行了表征.在紫外光照和可见光照条件下,研究了不同复合比例的复合物的光催化降解甲基蓝(MB)的性能.结果表明:在水热过程中氧化石墨烯被还原,通过静电引力相互作用得到了具有较高缺陷的还原氧化石墨烯复合物.随着RGO含量的增加,复合物的禁带宽度由3.00 eV变到2.27eV,复合物的导电性增强.在可见光和紫外光光照条件下, 30 min内1%(w,质量分数)RGO-P25光催化降解甲基蓝的效率都超过了80%.紫外光照条件下, 1%RGO-P25纳米复合物催化降解N3染料, cis-Ru(H₂dcbpy)₂(NCS)₂ (H₂dcbpy = 4, 4'-二羧酸-2, 2'-联吡啶), 30 min内63%(摩尔分数)的染料被降解.与P25(75%锐钛矿, 25%金红石)相比,石墨烯的加入大大提高了光催化效率,有效抑制了电子-空穴对的复合.     

泡沫镍及负载型镍催化剂制备纳米碳纤维层的研究

纳米碳纤维可用在催化材料、储氢材料、及纳米电子器件等方面。本文对用泡沫镍及负载型镍催化剂催化分解乙烯或丙烯制备纳米碳纤维进行了研究。利用X射线衍射仪、物理吸附仪、扫描电镜进行了分析表征,并考察了催化剂、碳源、生长温度对纳米碳纤维生长量、形貌、结构的影响。结果表明:在生长温度450℃,乙烯流率30mL/m in的条件下,负载型镍催化剂纳米碳纤维的生长量要高出泡沫镍3~6倍,负载型镍催化剂制备的纳米碳纤维直径为40~60纳米,小于泡沫镍的情况。泡沫镍催化分解乙烯制备纳米碳纤维时,纳米碳纤维的生长量和平均直径随温度的降低而逐渐减小。纳米碳纤维在泡沫镍上的最低生长温度为420℃,在低于480℃生长纳米碳纤维时泡沫镍的骨架结构不会被破坏,由此制备的纳米碳纤维在新型结构催化材料中有很好的的应用前景。     

镍铁水滑石/还原氧化石墨烯的制备及电催化水氧化性能

首先制备了不同镍/铁比的镍铁水滑石, 并通过液相剥离法得到水滑石纳米薄片溶胶, 随后将其与还原氧化石墨烯复合, 并对其进行了电催化水氧化的性能测试. 结果表明, 镍铁水滑石的剥离可以大幅度提高其电催化性能, 起峰电位为1.47 V, 电流密度为10 mA/cm² 时, 电位仅为1.53 V; 与还原氧化石墨烯复合后, 其催化活性得到了进一步提高, 在10 mA/cm²时电位降为 1.515 V.     

钴酸镍纳米花/活性炭纤维复合物的制备和表征及其超级电容器性能

利用简单的水热法以及后续热处理, 将钴酸镍纳米花成功生长在活性炭纤维支架上. 场发射扫描电镜(FESEM)及透射电镜(TEM)结果表明, 纳米花是由纳米针自组装而成, 而纳米针呈多孔结构. 这种三维复合多级结构非常有利于电解质离子的渗透和电子的传输. 将该多孔钴酸镍纳米花/活性炭纤维布作为工作电极, 表现出优良的电容性能. 在1 A·g^-1时, 比电容高达1626 F·g^-1; 在10 A·g^-1时, 电容保持率为65%, 具有超高的电容值和优异的倍率特性.     

水热法制备氧化钇空心纳米花及其吸附性能

采用水热法制备单分散、粒径均一的碱式碳酸钇(Y(OH)CO3)前驱体,经过高温煅烧处理得到氧化钇(Y_2O_3)空心纳米花。通过傅里叶转换红外分析(FT-IR),场发射扫描电子显微镜(FESEM),透射电子显微镜(TEM),X射线衍射(XRD),X射线能谱(XPS)以及N2吸-脱附等来表征样品,并研究了Y_2O_3空心纳米花吸附重铬酸钾(K2Cr2O7)的能力。实验结果表明:水热法制备的前驱体为Y(OH)CO3,经高温煅烧处理得到立方相Y_2O_3空心纳米花,尺寸约140 nm,比表面积为15 m2·g-1,讨论了Y_2O_3空心纳米花的形成机理。水热法制备的Y_2O_3空心纳米花对K2Cr2O7溶液的去除率可高达88.5%,吸附量为11.06 mg·g-1,约为Y_2O_3粉末的6倍。     

水热法制备氧化钇空心纳米花及其吸附性能

采用水热法制备单分散、粒径均一的碱式碳酸钇(Y(OH)CO₃)前驱体,经过高温煅烧处理得到氧化钇(Y₂O₃)空心纳米花。通过傅里叶转换红外分析(FT-IR),场发射扫描电子显微镜(FESEM),透射电子显微镜(TEM),X射线衍射(XRD),X射线能谱(XPS)以及N₂吸-脱附等来表征样品,并研究了Y₂O₃空心纳米花吸附重铬酸钾(K₂Cr₂O₇)的能力。实验结果表明:水热法制备的前驱体为Y(OH)CO₃,经高温煅烧处理得到立方相Y₂O₃空心纳米花,尺寸约140 nm,比表面积为15 m²·g^-1,讨论了Y₂O₃空心纳米花的形成机理。水热法制备的Y₂O₃空心纳米花对K₂Cr₂O₇溶液的去除率可高达88.5%,吸附量为11.06 mg·g^-1,约为Y₂O₃粉末的6倍。     

三维Ni(OH)2/Ni@N掺杂还原氧化石墨烯复合电极的制备及电催化析氢性能

采用脱合金结合两步水热法将3D Ni （OH）₂/Ni与N掺杂还原氧化石墨烯（rGO）结合,成功制备出3D花状Ni （OH）₂/Ni@NG复合电极。通过X射线衍射（XRD）、X射线光电子能谱（XPS）、扫描电子显微镜（SEM）和透射电子显微镜（TEM）表征其物相、价态分布及微观结构。在1 mol·L^-1 KOH溶液中测试其电催化析氢反应（HER）性能。结果表明：Ni （OH）₂/Ni的3D结构增加了电极的活性面积,与N掺杂rGO复合显著提高了电子/离子的传输速率,其过电位为108 mV （η₁₀）,Tafel斜率为114.9 mV·dec^-1,表现出良好的HER催化活性。1 000圈循环伏安法及计时电位法测试表明,Ni （OH）₂/Ni@NG电极均表现出良好的稳定性。     

碳纳米管负载纳米Ni修饰电极及碱液中电氧化甲醇

采用湿化学法在碳纳米管(MWCNTs)上负载Ni纳米粒子(MWCNTs-Ni),并制备MWCNTs-Ni修饰玻碳电极(MWCNTs-Ni/GCE),用X射线粉末衍射和透射电子显微镜测试技术对MWCNTs-Ni的物相和形貌进行了表征,通过循环伏安法研究了该修饰电极在碱性介质中的电化学行为以及对甲醇的电催化氧化作用。结果表明,面心立方的Ni纳米粒子均匀分散在碳纳米管表面,平均粒径约为16 nm,MWCNTs-Ni/GCE在碱性介质中的电化学行为是受扩散控制的准可逆过程,对甲醇的电催化氧化具有较高的电催化活性。     

Integrated Bismuth Oxide Ultrathin Nanosheets/Carbon Foam Electrode for Highly Selective and Energy-Efficient Electrocatalytic Conversion of CO2 to HCOOH

Electroreduction of CO₂ into formic acid (HCOOH) is of particular interest as a hydrogen carrier and chemical feedstock. However, its conversion is limited by a high overpotential and low stability due to undesirable catalysts and electrode design. Herein, an integrated 3D bismuth oxide ultrathin nanosheets/carbon foam electrode is designed by a sponge effect and N-atom anchor for energy-efficient and selective electrocatalytic conversion of CO₂ to HCOOH for the first time. Benefitting from the unique 3D array foam architecture for highly efficient mass transfer, and optimized exposed active sites, as confirmed by density functional theory calculations, the integrated electrode achieves high electrocatalytic performance, including superior partial current density and faradaic efficiency (up to 94.1 %) at a moderate overpotential as well as a high energy conversion efficiency of 60.3 % and long-term durability.     

Nanostructures for Electrocatalytic CO2 Reduction

One of the most effective ways to cope with the problems of global warming and the energy shortage crisis is to develop renewable and clean energy sources. To achieve a carbon-neutral energy cycle, advanced carbon sequestration technologies are urgently needed, but because CO₂ is a thermodynamically stable molecule with the highest carbon valence state of +4, this process faces many challenges. In recent years, electrochemical CO₂ reduction has become a promising approach to fix and convert CO₂ into high-value-added fuels and chemical feedstock. However, the large-scale commercial use of electrochemical CO₂ reduction systems is hindered by poor electrocatalyst activity, large overpotential, low energy conversion efficiency, and product selectivity in reducing CO₂. Therefore, there is an urgent need to rationally design highly efficient, stable, and scalable electrocatalysts to alleviate these problems. This minireview also aims to classify heterogeneous nanostructured electrocatalysts for the CO₂ reduction reaction (CDRR).     

Metal-Based Aerogels Catalysts for Electrocatalytic CO2 Reduction

General strategies for metal aerogel synthesis, including single-metal, transition-metal doped, multi-metal-doped, and nano-metal-doped carbon aerogel are described. In addition, the latest applications of several of the above-mentioned metal aerogels in electrocatalytic CO₂ reduction are discussed. Finally, considering the possibility of future applications of electrocatalytic CO₂ reduction technology, a vision for industrialization and directions that can be optimized are proposed.     

双二苯基-1-甲基咪唑膦氯化镍的制备及其电催化还原CO2的研究

以二苯基-1-甲基咪唑膦（dpim）为配体制备了一种新型的配合物催化剂Ni(dpim)₂Cl₂. 循环伏安研究表明,Ni(dpim)₂Cl₂配合物在氮气气氛下表现出两步还原的电化学行为,在-0.7 V下为两电子的不可逆还原,在-1.3 V下为单电子准可逆还原. 向电解液中通入CO₂后,在-1.3 V下的还原峰变得不可逆,且其峰电流从0.48 mA·cm^-2增大到0.55 mA·cm^-2. 在质子源（CH₃OH）存在的条件下,该还原峰电流可继续增大到0.72 mA·cm^-2. 该研究结果表明,Ni(dpim)₂Cl₂配合物对CO₂还原具有良好的电催化性能,且其电催化还原过程符合ECE机理. 在-1.3 V下恒电位电解得到的还原产物主要为CO,催化转换频率（Turnover of Frenquency, TOF）为0.17 s^-1.     

Surface Reconstruction of Ultrathin Palladium Nanosheets during Electrocatalytic CO2 Reduction

A surface reconstructing phenomenon is discovered on a defect-rich ultrathin Pd nanosheet catalyst for aqueous CO₂ electroreduction. The pristine nanosheets with dominant (111) facet sites are transformed into crumpled sheet-like structures prevalent in electrocatalytically active (100) sites. The reconstruction increases the density of active sites and reduces the CO binding strength on Pd surfaces, remarkably promoting the CO₂ reduction to CO. A high CO Faradaic efficiency of 93 % is achieved with a site-specific activity of 6.6 mA cm⁻² at a moderate overpotential of 590 mV on the reconstructed 50 nm Pd nanosheets. Experimental and theoretical studies suggest the CO intermediate as a key factor driving the structural transformation during CO₂ reduction. This study highlights the dynamic nature of defective metal nanosheets under reaction conditions and suggests new opportunities in surface engineering of 2D metal nanostructures to tune their electrocatalytic performance.     

Electrocatalytic CO2 Reduction with a Half‐Sandwich Cobalt Catalyst: Selectivity towards CO

We present herein a Cp*Co(III)‐half‐sandwich catalyst system for electrocatalytic CO₂ reduction in aqueous acetonitrile solution. In addition to an electron‐donating Cp* ligand (Cp*=pentamethylcyclopentadienyl), the catalyst featured a proton‐responsive pyridyl‐benzimidazole‐based N,N‐bidentate ligand. Owing to the presence of a relatively electron‐rich Co center, the reduced Co(I)‐state was made prone to activate the electrophilic carbon center of CO₂. At the same time, the proton‐responsive benzimidazole scaffold was susceptible to facilitate proton‐transfer during the subsequent reduction of CO₂. The above factors rendered the present catalyst active toward producing CO as the major product over the other potential 2e/2H⁺ reduced product HCOOH, in contrast to the only known similar half‐sandwich CpCo(III)‐based CO₂‐reduction catalysts which produced HCOOH selectively. The system exhibited a Faradaic efficiency (FE) of about 70% while the overpotential for CO production was found to be 0.78 V, as determined by controlled‐potential electrolysis.     

Catholyte‐Free Electrocatalytic CO2 Reduction to Formate

Electrochemical reduction of carbon dioxide (CO₂) into value‐added chemicals is a promising strategy to reduce CO₂ emission and mitigate climate change. One of the most serious problems in electrocatalytic CO₂ reduction (CO₂R) is the low solubility of CO₂ in an aqueous electrolyte, which significantly limits the cathodic reaction rate. This paper proposes a facile method of catholyte‐free electrocatalytic CO₂ reduction to avoid the solubility limitation using commercial tin nanoparticles as a cathode catalyst. Interestingly, as the reaction temperature rises from 303 K to 363 K, the partial current density (PCD) of formate improves more than two times with 52.9 mA cm^?2, despite the decrease in CO₂ solubility. Furthermore, a significantly high formate concentration of 41.5 g L^?1 is obtained as a one‐path product at 343 K with high PCD (51.7 mA cm^?2) and high Faradaic efficiency (93.3 %) via continuous operation in a full flow cell at a low cell voltage of 2.2 V.     

氮化铌电催化还原CO2

通过电化学的方法将CO₂转化为CO是解决资源和环境问题的经济友好的策略。在本次工作中,利用湿化学方法制备了铌/碳的前驱体,在NH₃和Ar氛围下煅烧后分别转化为Nb₄N₅/C和Nb₂O₅/C。当氮化温度达到700℃时,制备的Nb₄N₅/C表现出优异的催化活性,在CO₂饱和的0.5 mol·L^-1的NaCl溶液中,电解电位为-0.83V（RHE）时,CO的法拉第效率最高,达到57%。实验结果表明,Nb₄N₅/C的催化活性与Nb₄N₅中的N掺杂有关。