Deciphering engineering principle of three-phase interface for advanced gas-involved electrochemical reactions

As an alternative to conventional energy conversion and storage reactions, gas-involved electrochemical reactions, including the carbon dioxide reduction reaction(CO₂RR), nitrogen reduction reaction(NRR)and hydrogen evolution reaction(HER), have become an emerging research direction and have gained increasing attention due to their advantages of environmental friendliness and sustainability. Various studies have been designed to accelerate sluggish kinetics but with limited results. M...     

Nanocarbon-based metal-free and non-precious metal bifunctional electrocatalysts for oxygen reduction and oxygen evolution reactions

The oxygen reduction/evolution reactions (ORR/OER) are a key electrode process in the development of electrochemical energy conversion and storage devices,such ...     

原位拉曼光谱与X射线吸收光谱研究能源转换电催化反应

近年来,水分解、氧气/二氧化碳还原等电化学能源转换技术为解决全球能源短缺及环境问题提供了新的思路和方向.然而,对这些能源转换技术的反应机理及其催化剂的活性位点目前仍缺乏深刻的认识和理解,这限制了高效、稳定催化剂的开发,以致阻碍该类电化学技术的进一步发展.原位光谱技术的快速发展为解决上述问题提供了坚实的基础,其中拉曼光谱...     

Polyelectrolyte functionalized carbon nanotubes as efficient metal-free electrocatalysts for oxygen reduction

Having a strong electron-withdrawing ability, poly(diallyldimethylammonium chloride) (PDDA) was used to create net positive charge for carbon atoms in the nanotube carbon plane via intermolecular charge transfer. The resultant PDDA functionalized/adsorbed carbon nanotubes (CNTs), either in an aligned or nonaligned form, were demonstrated to act as metal-free catalysts for oxygen reduction reaction (ORR) in fuel cells with similar performance as Pt catalysts. The adsorption-induced intermolecular charge-transfer should provide a general approach to various carbon-based efficient metal-free ORR catalysts for oxygen reduction in fuel cells, and even new catalytic materials for applications beyond fuel cells.     

碳基无金属氧还原电催化剂研究的新进展

以替代铂为目标的高性能廉价氧还原电催化剂的研究为当今科学前沿. 近年来人们发现, 掺杂的碳基纳米结构具有催化活性高、稳定性好、资源丰富、抗CO和抗甲醇能力强等优点, 是一种新型无金属氧还原电催化剂, 具有替代铂基催化剂的潜力. 本文结合作者课题组的最新研究成果, 简要综述了碳基无金属氧还原电催化剂研究的主要进展, 重点关注了富电子氮和缺电子硼单/共掺杂的碳纳米结构的氧还原催化性能及其与电子结构的关系, 展望了碳基无金属氧还原催化剂的发展策略与前景.     

原子层沉积方法在设计制备高效电催化剂中的应用（英文）

人类对不可再生化石能源的依赖导致了全球范围内的能源危机和环境污染.电化学能源转换技术由于具有清洁、高效、原料来源广泛及可再生等优点而受到广泛关注.电催化剂能加快反应动力学,提高目标产物选择性,在电化学能源转换技术中起着至关重要的作用.目前, Pt是多数重要的电化学反应(如电解水、氧还原以及一些小分子醇类和酸类的氧化反应)中使用最多和最有效的催化剂之一.然而Pt催化剂面临着价格昂贵、易中毒、易流失等问题,使其在大规模工业化应用中受到限制.为了提高Pt催化剂的利用率和稳定性,研究人员进行了大量工作.例如,制备尺寸小的Pt纳米颗粒,增加单位质量Pt表面积和Pt利用率;在Pt催化剂中加入Ru或Pd等其它金属,促进醇类和酸类氧化反应中间产物的氧化,减缓Pt中毒;选用抗腐蚀性能好的载体,增加Pt与载体间相互作用,从而抑制Pt颗粒在高电位、高湿度、高酸碱度电化学工作环境中的脱落和聚集.尽管如此,利用传统的方法仍然很难精确调控电催化剂的组成、尺寸和纳米结构,无法最大程度提高贵金属Pt的利用效率.原子层沉积(ALD)技术可在原子尺度控制物质生长,既能在多孔、复杂基体上沉积尺度均一的纳米薄膜或颗粒,也能精...     

Coupling interface engineering with electronic interaction toward high-efficiency H2 evolution in pH-universal electrolytes

Herein, the merits of heterojunction, CeO₂, and W are employed to design and prepare the PtCoW@CeO₂ heterojunction catalyst, which can accelerate water dissociation and improve the desorption of OH_ad, displaying efficient hydrogen evolution reaction(HER) performance in pH-universal conditions. Density functional theory calculation results reveal that the electronic structure of Pt is regulated by CeO₂ and W, which tunes the Pt–H_ad bond stren...     

Defect and interface engineering for electrochemical nitrogen reduction reaction under ambient conditions

Electrochemical nitrogen reduction reaction(e-NRR)under ambient conditions is an emerging strategy to tackle the hydrogen-and energy-intensive operations for traditional Haber-Bosch process in industrial ammonia(NH₃)synthesis.However,the e-NRR performance is currently impeded by the inherent inertness of N₂ molecules,the extremely slow kinetics and the overwhelming competition from the hydrogen evolution reaction(HER),all of which cause unsatisfied yield and ammonia selectivity(Faradaic efficiency,FE).Defect and interface engineering are capable of achieving novel physical and chemical properties as well as superior synergistic effects for various electrocatalysts.In this review,we first provide a general introduction to the NRR mechanism.We then focus on the recent progress in defect and interface engineering and summarize how defect and interface can be rationally designed and functioned in NRR catalysts.Particularly,the origin of superior NRR catalytic activity by applying these approaches was discussed from both theoretical and experimental perspectives.Finally,the remaining challenges and future perspectives in this emerging area are highlighted.It is expected that this review will shed some light on designing NRR electrocatalysts with excellent activity,selectivity and stability.     

Rational catalyst design and interface engineering for electrochemical CO2 reduction to high-valued alcohols

Electrochemical CO₂ reduction(eCO₂RR) is an emerging strategy to address the global carbon balance issues and fulfill the carbon-neutral goal through converting CO₂ to value-added chemicals/fuels driven by renewable energy sources. The production of highly reduced carbon compounds beyond CO and formate, especially oxygenate alcohol products with high energy densities and large global market capacities, is particularly desirable for practical applications. However...     

Nanoporous graphitic-C3N4@carbon metal-free electrocatalysts for highly efficient oxygen reduction

Based on theoretical prediction, a g-C(3)N(4)@carbon metal-free oxygen reduction reaction (ORR) electrocatalyst was designed and synthesized by uniform incorporation of g-C(3)N(4) into a mesoporous carbon to enhance the electron transfer efficiency of g-C(3)N(4). The resulting g-C(3)N(4)@carbon composite exhibited competitive catalytic activity (11.3 mA cm(-2) kinetic-limiting current density at -0.6 V) and superior methanol tolerance compared to a commercial Pt/C catalyst. Furthermore, it demonstrated significantly higher catalytic efficiency (nearly 100% of four-electron ORR process selectivity) than a Pt/C catalyst. The proposed synthesis route is facile and low-cost, providing a feasible method for the development of highly efficient electrocatalysts.     

Catalytic amplification based on hole-transporting materials as efficient metal-free electrocatalysts for non-enzymatic glucose sensing

Hole-transporting materials with tunable structures and properties are mainly applied in organic light-emitting diodes as transport layer. But their catalytic properties as signal amplifiers in biological assays are seldom reported. In this paper, a starburst molecule, 4,4,4″-tri(N-carbazolyl)-triphenylamine (TCT), containing a triphenylamine as the central core and three carbazoles as the peripheral functional groups was designed and synthesized. Subsequently, the hole-transporting material based on the TCT polymer, poly(TCT) (PTCT), was achieved via a low-cost electrochemical method and exploited as an efficient metal-free electrocatalyst for non-enzymatic glucose detection. Here, this hole-transporting material served three purposes: electrochemical recognition (owing to hydrogen bonding interaction and the biomimetic microenvironment created by the polymer), electrocatalysis (owing to the hole-transporting capability of triphenylamine and the catalytic property of carbazole), and signal amplification (owing to energy migration along the conductive polymer backbone). The electrocatalytic and sensing performances of the sensor based on PTCT were evaluated in detail. Results revealed that the PTCT film could efficiently catalyze the oxidation of glucose at a less-positive potential (+0.20 V) in the absence of any enzymes. The response to glucose was linear in the concentration range of 1.0–6000 μM, and the detection limit was 0.20 μM. With good stability and selectivity, the proposed sensor could be feasibly applied to detect glucose in practical samples. The encouraging sensing performances suggest that the hole-transporting material is one of the promising biomimetic catalysts for electrocatalysis and relevant fields.     

Platinum group metal-free oxygen reduction electrocatalysts used in neutral electrolytes for bioelectrochemical reactor applications

The oxygen reduction reaction is one of the limiting steps in microbial fuel cell performance. M–N–C catalysts (M as transition metal) represent the best compromise of optimal cost, electrocatalytic activity and durability. The Fe-based catalysts were shown to be the best compared with Co-, Mn-, Ni-based catalysts. The addition of the second transition metal such as Mn was shown to increase the selectivity of the reaction and reduce peroxide production. The use of different N–C precursors resulted in diverse surface chemistry that directly affects the performance. Generally, surface chemistry plays a critical role in the electrocatalytic activity. Integration of the catalyst in the air-breathing cathode is also discussed with a performance that is enhanced by: (i) increased catalyst loading; (ii) the addition of graphene to structure.     

Metal porphyrins as electrocatalysts for commercially important reactions

Transition Metal Chemistry -     

Combinatorial electrochemical screening of fuel cell electrocatalysts

Combinatorial methods have been applied to the preparation and screening of fuel cell electrocatalysts. Hardware and software have been developed for fast sequential measurements of cyclic voltammetric and steady-state currents in 64-element half-cell arrays. The arrays were designed for the screening of high-surface-area supported electrocatalysts. Analysis software developed allowed the semiautomated processing of the large quantities of data, applying filters that defined figures of merit relevant to fuel cell catalyst activity and tolerance. Results are presented on the screening of carbon-supported platinum catalysts of varying platinum metal loading on carbon (and thus, particle size) in order to demonstrate the speed and sensitivity of the screening methodology. CO electro-oxidation, oxygen reduction, and methanol oxidation on a series of such catalysts reveal clear trends in characteristics and activities. Catalysts with smaller particle sizes reveal structure in the CO stripping voltammetry that can be associated with edge sites in addition to the closely packed planes, and this is concomitantly reduced as particle size is increased. Specific activity for steady-state methanol oxidation and oxygen reduction at room temperature in H(2)SO(4) electrolyte is found to be a maximum for the largest particle sizes, in agreement with the literature. These trends in activity are significantly smaller than the differences in activities of promoted platinum-based alloy catalysts for the same reaction.     

含硒表界面化学

硒是人体必需的一种微量元素, 本课题组近年的研究表明含硒化学键具有诸多独特的化学性质. 二硒键具有氧化还原双重响应性, 同时是一类光响应的动态共价键, 能够在可见光辐照下发生可逆的交换反应. 将含硒化学键这些独特的性质与表界面化学相结合可以赋予体系独特的响应行为. 本文综合评述了本课题组近年来在含硒表界面化学领域的研究进展: 采用单分子力谱揭示了含硒化学键相互作用的力学规律; 通过表界面化学实现了二硒键动态平衡的调控; 基于二硒键氧化还原及可见光响应性实现了表界面可逆修饰、 二维材料功能化及层层组装膜材料的制备, 在生物医用、 液体输运等领域具有潜在应用价值.     

Engineering morphologies of cobalt oxide/phosphate-carbon nanohybrids for high-efficiency electrochemical water oxidation and reduction

Active non-noble metal catalysts plays a decisive role for water electrolysis,however,the rational design and development of cost-efficient electrocatalysts with Pt/IrO2-like activity is still a challenging task.Herein,a facile one-step electrodeposition route in deep eutectic solvents(DESs) is developed for morphology-controllable synthesis of cobalt oxide/phosphate-carbon nano hybrids on nickel foam(CoPO@C/NF).A series of CoPO@C/NF nanostructures including cubes,octahedrons,microspheres and nanoflowers are synthesized,which show promising electrocatalytic properties toward oxygen and hydrogen evolution reactions(OER/HER).Such surface self-organized microstructure with accessible active sites make a significant contribution to the enhanced electrochemical activity,and hybridizing cobalt oxide with cobalt pyrophosphates and carbon can result in enhanced OER performance through synergistic catalysis.Among all nanostructures,the obtained microspherical CoPO@C/NF-3 catalyst exhibits excellent catalytic activities for OER and HER in 1.0 M KOH,affording an anodic current density of 10 mA cm^-2 at overpotentials of 293 mV for OER and 93 mV for HER,with good long-time stability.This work offers a practical route for engineering the high-performance electrocatalysts towards efficient energy conversion and storage devices.