Boosting CO2 Electroreduction to Multi-carbon Products via Oxygen-rich Vacancies and Ce4+−O2−−Cu+ Structure in Cu/CeO2 for Stabilizing Cu+

Cu is a promising electrocatalyst for the CO₂ reduction reaction (CO₂RR) to produce high-value C₂₊ products. Due to the fierce competition of the hydrogen evolution reaction, the slow diffusion of CO₂, and the high energy barrier of the C−C coupling reaction, it is still challenging to achieve high activity and high selectivity to produce multi-carbon products on copper-based electrocatalysts. In this work, we synthesized Cu/CeO₂ catalysts with varying amounts of Cu doping, aiming at effectively converting CO₂ into C₂₊ products through electroreduction. At a copper doping level of 9.77 wt%, the catalyst exhibited a current density of 16.8 mA cm⁻² using a standard H-type cell, achieving a C₂₊ faradaic efficiency (FE) of 78.3 %. Through additional experiments and material characterization, we confirmed that controlling the Cu loading on the surface of CeO₂ is an effective way to regulate the ratio of Cu⁺ to Cu⁰ active sites and the number of oxygen vacancies. Furthermore, the strong electron interaction between Ce⁴⁺−O²⁻−Cu⁺ structure can stabilize Cu⁺ species and enhance the overall stability of the catalyst. This strategy enhances the selectivity towards C₂₊ products and effectively suppresses the competing hydrogen evolution reaction.     

单原子催化剂在电催化还原CO2领域的应用

温和条件下以CO₂为原料制备高附加值化学品, 是CO₂资源化利用的重要方法, 在众多CO₂转化方法中, 电催化CO₂还原(e-CO₂RR)具有绿色、 清洁及条件可控等优势, 可以促进碳中和, 实现可持续发展. 然而, 由于其缓慢的动力学和较低催化剂活性, CO₂电催化还原仍然存在低选择性, 低电流密度的问题. 单原子催化剂具有最大的原子利用率和明确定义的催化活性位点, 同时因其良好的配位结构和独特的电子结构极大地促进了CO₂电催化还原的动力学过程, 是CO₂电还原领域极具发展潜力的催化材料. 本文讨论了过渡金属和主族金属基单原子催化剂用于电催化CO₂还原的研究进展, 系统总结了杂原子配位, 双/单原子位点, 金属-载体相互作用, 空间限域和分子桥联等策略调控单原子的微环境进而优化催化的性能, 揭示了单原子催化剂在 e-CO₂RR领域内的突出优势和广阔的应用前景. 最后, 分析了单原子催化剂在CO₂电催化转化过程中面临的挑战, 并对其未来进行了展望.     

Porous Nanostructured Metals for Electrocatalysis

Nanoporous metals have been used to enhance electrocatalysis. The origin of their capability is understood on the basis of enlarged surface area. On the other hand, the nanoconfined space of nanoporous metals can significantly affect the electrochemical efficiency. Moreover, molecular dynamics in nanoconfined spaces is capable of offering much more chances of interaction between a redox molecule and a metal surface. These unique properties come from simply nanoporous structure and suggest new opportunity to innovative electrocatalysts in the future. This review addresses recent advances in the field of nanoporous metals and discusses respective important electrocatalytic applications.     

Determination of Some Phenothiazines Compounds in Pharmaceuticals and Human Body Fluid by Electrocatalytic Oxidation at a Glassy Carbon Electrode Using Methylene Blue as a Mediator

Abstract

A glassy carbon electrode plus Methylene blue as a mediator was employed to study and sense the electrocatalytic oxidation of phenothiazines, including chlorpromazine, perphenazine, promazine, and fluphenazine, using cyclic voltammetry and chronoamperometry as diagnostic techniques. The electron-transfer coefficient, alpha (= 0.45), for phenothiazines compounds at the surface of glassy carbon electrode was determined using a cyclic voltammetry technique. It was found that under a selected pH (8.6) the peak current due to the oxidation of Methylene blue at the surface of the electrode that occurrs at a potential of about ? 180 mV is proportional to the phenothiazines concentration. Linear analytical curves were obtained in the ranges of 1.0 × 10^?6 ? 2.1 × 10^?4 mol L^?1 for the phenothiazines compounds. The influences of potentially interfering substances on the current response of the system were examined. The method was used for the determination of phenothiazines compounds, including chlorpromazine, perphenazine, promazine, and fluphenazine in human.     

A powerful approach to fabricate nitrogen-doped graphene sheets with high specific surface area

This study develops a powerful strategy for fabricating the nitrogen-doped graphene sheets with good crystallinity, high specific surface area, and high percentages of pyridinic/graphitic-nitrogen structures. Due to the specified N-doping structures and high specific surface area of 719 m² g^− 1, our N-doped graphene sheets show an excellent electrocatalytic activity for the oxygen reduction reaction (ORR).     

Electrocatalytic activity of non-precious metal catalyst Co-N/C toward oxygen reduction reaction

<正>Metallic cobalt was deposited on acetylene black to synthesize a composite Co/C by chemical reduction method.A platinumfree electrocatalyst Co-N/C(800) for oxygen reduction reaction(ORR) was synthesized by mixing the composite Co/C with urea and heat-treating at 800℃.The results from linear sweep voltammograms indicated that the Co-N/C(800) is active to ORR.Theβ-Co and cobalt oxides are not the active site of the catalyst Co-N/C.However,the existence of cobalt facilitated the modification of nitrogen to carbon black and led to the formation of active site of catalyst Co-N/C(800).     

基于Cu(Ⅱ) Tricine配合物制备氧化铜薄膜及其电催化水氧化活性

众所周知, 传统化石燃料的大量使用不仅导致严重的环境污染和温室效应, 而且化石能源本身也面临着枯竭的危机.所以, 探索全新的、环境友善的、可持续发展的能源载体一直备受国内外科研工作者的关注. 氢能是一种清洁的可再生能源, 是有潜力的化石能源替代品. 水分解是一种有效的、理想的产氢途径, 然而水氧化反应是多质子多电子传递的过程, 是制约整个水分解过程的瓶颈. 目前, 基于贵金属(铱和钌)分子和氧化物的电催化剂已经被报道很多, 并且可以保持很好的催化活性; 但是, 这一类催化剂差的稳定性、昂贵的价格和少的地壳含量等因素严重制约了其大规模实际应用. 因此, 开发基于非贵金属(钴、镍、铁、铜、锰)的新型电催化剂材料是解决该问题的唯一出路, 但要保证电催化剂的高活性和好的稳定性仍面临着诸多挑战.在众多的非贵金属中, 铜是一种来源广泛的金属, 而且铜对生物体毒性较小. 由于铜具有良好的配位化学和多重的氧化还原特性, 近年来, 很多基于铜的水氧化电催化剂被开发和研究.我们在含有1.0 mmol/L Cu2+和2.0 mmol/L Tris配体的磷酸缓冲溶液(0.2 mol/L, pH = 12.0)中, 采用1.15 V vs. NHE恒电位电沉积的方法, 在ITO导电玻璃上制备出基于铜的水氧化催化剂薄膜(Cu-tricine). 对得到的催化剂薄膜进行扫描电镜(SEM)测试, 该催化剂均匀负载在ITO表面, 厚度大约是1.4 μm. 为了更加深入研究Cu-Tricine催化剂薄膜, 采用透射电子显微镜(TEM)和X射线衍射(XRD)对Cu-tricine催化剂进行表征, 结果表明, 该催化剂薄膜是一种结晶度较差的无定形材料. 同时, 为了研究催化剂薄膜的元素组成及其所处状态, 对催化剂进行了能量散射X射线能谱(EDX)和X射线光电子能谱(XPS)测试, 结果表明, 该催化剂由铜和氧元素组成, 并且铜是以正二价存在. 由高分辨O 1s XPS谱图分析结果可以推测, Cu-Tricine催化剂可能是由氧化铜和氢氧化铜组成. Cu-tricine催化剂的水氧化活性是在0.2 mol/L的磷酸缓冲溶液(pH =12.0)中进行测试, 从塔菲尔曲线中可以得出, 该催化剂达到1.0 mA/cm2的催化电流密度所需的过电位是395 mV, 塔菲尔斜率为46.7 mV/decade. 此外, 在1.15 V vs. NHE的电位下, 在10 h的电解过程中, Cu-tricine催化剂薄膜可以将催化电流密度一直保持在7.5 mA/cm2, 并且得到的法拉第效率为99%.     

多壳层中空FeP微球的制备及全Ph范围的电催化产氢性能

设计合成了一种多壳层中空多孔结构的磷化铁(FeP)微球, 通过扫描电子显微镜(SEM)、 透射电子显微镜(TEM)、 X射线衍射(XRD)和X射线光电子能谱(XPS)对微球的表面形貌和物相组成等进行表征, 并通过电化学工作站测试了材料的析氢性能. 结果表明, FeP微球和掺杂导电剂碳纳米管(CNT)后的FeP/CNT复合电催化剂在宽pH范围的电解液中均展现出了优异的电催化活性, 在酸性、 碱性和中性条件下析氢反应过程中的塔菲尔斜率分别为55.0, 64.9, 163.2 mV/dec, 当电流密度达到10 mA/cm ²时, 过电势仅分别为97, 169, 495 mV(vs. RHE), 且表现出了超长的循环稳定性.     

Ruthenium-based electrocatalysts for oxygen reduction reaction—a review

A major impediment to the commercialization of fuel cells is the low activity of electrocatalysts for the oxygen reduction reaction that involves multiple electron transfer steps. Platinum is considered the best cathode catalyst toward oxygen reduction to water; however, Pt remains an expensive metal of low abundance, and it is of great importance to find Pt-free metal alternatives. Among various Pt-free catalysts under development, ruthenium-based compounds show significant catalytic activity and selectivity for four-electron reduction of oxygen to water in acidic environments. This article provides a short review on the different classes of Ru-based catalysts focusing on the catalytically active reaction sites and the oxygen reduction mechanism in acidic media. After a brief discussion of the oxygen reduction kinetics on a pure Ru metal, the paper reviews the catalytic properties of the selected Ru compounds, including crystalline Chevrel-phase chalcogenides, nanostructured Ru and Ru–Se clusters, and Ru–N chelate compounds. This paper is dedicated to Professor Su-Il Pyun, who has pioneered advances in interfacial electrochemistry in the field of corrosion and materials science in South Korea, on the occasion of his 65th birthday.     

Investigation of electrochemical performance of sol-gel derived MgFe2O4 nanospheres as aqueous supercapacitor electrode and bi-functional water splitting electrocatalyst in alkaline medium

Herein this work, we have used the sol-gel chemical synthesis method to prepare spherical shaped MgFe₂O₄ nanoparticles having size 45–50 nm. Using 1 mol L⁻¹ Sodium Perchlorate (NaClO₄) electrolyte, a capacitance of 61 F/g, a capacitance retention of 82.91% (after undergoing 1000 cycles), and an energy density of 41 Wh/kg have been achieved. Using 1 mol L⁻¹ Magnesium Perchlorate (Mg(ClO₄)₂) as electrolyte, a capacitance of 43 F/g, a capacitance retention of 82.15%, and an energy density of 29 Wh/kg have been realized. Furthermore, MgFe₂O₄ nanospheres exhibited an overpotential (η) = 1.09 V, a Tafel slope (b) = 317 mV/dec in regard to alkaline Oxygen Evolution Reaction (OER) electrocatalyst. It also achieved η = 402 mV and b = 241 mV/dec in regard towards alkaline Hydrogen Evolution Reaction (HER) electrocatalyst. These results signify the suitability of MgFe₂O₄ nanoparticles for high energy density aqueous supercapacitor and water splitting electrocatalyst applications.