Engineering heterostructure and crystallinity of Ru/RuS2 nanoparticle composited with N-doped graphene as electrocatalysts for alkaline hydrogen evolution

Crystalline engineering and heterostructure have attracted much attention as effective strategies to improve the electrocatalytic activity for hydrogen evolution reaction (HER). In this study, a new heterostructure catalyst (Ru/RuS₂@N-rGO) with low crystallinity was fabricated by a simple and low-temperature method for HER in alkaline solution, applying the Na₂SO₄ as S source and polypyrrole as N source. Optimizing through the controllable crystalline engineering and composition ratio of Ru and RuS₂, the Ru/RuS₂@N-rGO heterocatalyst at the calcining 500 °C revealed highly efficient HER activity with overpotential 18 mV at a current density 10 mA/cm² and remarkable stability for 24 h in 1.0 mol/L KOH. This work provides a facile and effective method in designing advanced electrocatalysts for HER in the alkaline electrolytes by synergistically structural and component modulations.     

Electrochemical hydrogen evolution efficiently boosted by interfacial charge redistribution in Ru/MoSe2 embedded mesoporous hollow carbon spheres

The strong metal-support interaction inducing combined effect plays a crucial role in the catalysis reaction. Herein, we revealed that the combined advantages of MoSe₂, Ru, and hollow carbon spheres in the form of Ru nanoparticles(NPs) anchored on a two-dimensionally ordered MoSe₂ nanosheet-embedded mesoporous hollow carbon spheres surface(Ru/MoSe₂@MHCS) for the largely boosted hydrogen evolution reaction(HER) performance. The combined advantages from the conduct...     

A candy-like photocatalyst by wrapping Co,N-co-doped hollow carbon sphere with ultrathin mesoporous carbon nitride for boosted photocatalytic hydrogen evolution

Hierarchical carbon material is used as a star cocatalyst in the field of photocatalysis due to its excellent catalytic properties. In this work, mesoporous carbon nitride sheet (MCNS) photocatalyst introduced nitrogen-doped hollow carbon spheres assembled with cobalt nanoparticles (Co@NHC) is synthesized by electrostatic adsorption. A series of characterizations are analyzed to display the structures, morphologies and optical properties of as-prepared materials. The photocatalytic activity of Co@NHC/MCNS material is evaluated with hydrogen evolution under visible light irradiation. The results indicate that 5 wt% Co@NHC/MCNS material reveals higher photocatalytic activity of hydrogen evolution rate of 3675 µmol/g with 4 h reaction time, which is 159 times than that of pure MCNS material. The carbon material with excellent charge transport properties can effectively accelerate the charge transfer from ultrathin MCNS to cobalt nanoparticles. The goal of improving the photocatalytic performance of Co@NHC/MCNS material is achieved. As a result, it provides a feasible and promised approach for doping transition metals to enhance photocatalytic activity.     

红毛丹状磷化钴@钼钴氧空心微米小球用于碱性电催化析氢（英文）

氢气因其能量密度高、零排放和可再生的特点被广泛认为是最有前景的能源.电解水是一种产生高纯氢气的有效途径.目前,高性能的促进水电解的催化剂主要是贵金属材料,例如贵金属铂.然而,高成本大大阻碍了贵金属材料在电催化水分解中的广泛应用.因此,我们致力于研究具有高活性的非贵金属催化剂.因为电催化水分解析氢反应更容易发生在质子浓度高的条件下,所以研究碱性条件下催化析氢比研究酸性条件下催化析氢更具挑战性.在工业应用中,酸性电解质溶液对仪器设备的腐蚀性比碱性溶液更大,因此研究应用在碱性溶液中的析氢催化剂更有发展前景.过渡金属磷化物被广泛地研究作为高性能析氢电催化剂,然而过渡金属磷化物作为析氢催化剂的稳定性通常不是很好.我们通过钼元素的引入,提高过渡金属磷化物作为析氢催化剂的稳定性.电化学催化效率同样受到材料形貌和导电性的影响.大的比表面积有利于暴露更多的活性位点,使活性位点与电解质溶液的接触更加充分,有利于催化剂和溶液之间的传质.据报道,金属磷化物具有良好的导电性是由于磷化物中存在金属-金属键.所以合成具有大比表面积形貌的过渡金属磷化物材料能够满足析氢电催化剂对比表面积和导电性的两个需求.界面效应是调节催化剂性能的一个有效方法.析氢催化剂常常存在吸附质子能力过强或过弱、稳定性不好等问题.这些问题可以通过界面效应来解决.本文通过形成磷化估和钼钴氧的界面来调节改善磷化钴表面原来的电子密度,以达到理想的氢吸附自由能;同时此界面效应还能起到稳定催化剂性能的作用.本文首先采用水热法合成了红毛丹状钼钴氧空心微米小球前驱体.在钼酸根离子的引导下,利用奥斯特瓦尔德熟化原理一步实现了红毛丹状空心结构.前驱体再以次亚磷酸钠为磷源进行气相磷化,得到产物红毛丹状磷化钴@钼钴氧空心微米小球.通过扫描电镜和透射电镜对其红毛丹状空心结构进行了表征.利用X射线衍射和X射线光电子能谱等手段表征了材料的物相组成和价态分布.电化学测试均使用电化学工作站完成.该材料在碱性电解质溶液中展现了极好的电化学催化析氢性能,在电流密度为10 mA cm^-2时对应的析氢过电位仅为62 mV.在1 MKOH溶液中10 mA cm^-2电流密度下测试55 h,过电位仅增大约17 mV,显示了非常强的碱性析氢稳定性.得益于磷化钴和钼钴氧之间的界面效应,以及特殊的三维空心结构,红毛丹状磷化钴@钼钴氧空心微米小球表现出优异的析氢催化性能和稳定性.     

Rational design of Ru species on N-doped graphene promoting water dissociation for boosting hydrogen evolution reaction

In this study,the morphological distribution of Ru on nitrogen-doped graphene (NG) could be rationally regulated via modulating the combination mode between Ru precursor and the zeolite imidazolate framework-8 (ZIF-8).The cation exchange and host-guest strategies respectively resulted in two different combination modes between Ru precursor and ZIF-8 anchored on graphene.Following pyrolysis of the above precursors,Ru single-atom sites (SASs) with and without Ru nanoparticles (NPs)were formed sele...     

Enhanced catalytic activity of Ru through N modification toward alkaline hydrogen electrocatalysis

Exploring highly efficient electrocatalysts and understanding the reaction mechanisms for hydrogen electrocatalysis,including hydrogen oxidation reaction （HOR） and hydrogen evolution reaction （HER） in alkaline media are conducive to the conversion of hydrogen energy.Herein,we reported a new strategy to boost the HER/HOR performances of ruthenium （Ru） nanoparticles through nitrogen （N） modification.The obtained N-Ru/C exhibit remarkable catalytic performance,with normalized HOR exchange current d...     

NiFe水滑石纳米片阵列负载Ru用于提升碱性电催化析氢和析氧性能

通过离子交换的方式将Ru负载到NiFe水滑石(LDH)纳米阵列表面得到(Ru/NiFe LDH),Ru的引入显著提升了NiFe LDH的活性比表面积,暴露了更多的活性位点,同时调控了其电子结构,大大提升了其本征催化活性。在碱性条件下,催化析氢反应时仅需50 mV的过电位即可达到10 mA·cm^-2的电流密度,Tafel斜率为52.3 mV·dec^-1。而相同条件下原始NiFe LDH达到10mA·cm^-2的电流密度则需要226 mV的过电位,Tafel斜率为157.5 mV·dec^-1。同时制备的Ru/NiFe LDH也展现出了良好的析氧催化活性,在50 mA·cm^-2的电流密度下,过电位仅为231 mV,而NiFe LDH则需237 mV。Ru/NiFe LDH在长时间的电催化条件下依然能保持良好的工作稳定性。     

NiFe水滑石纳米片阵列负载Ru用于提升碱性电催化析氢和析氧性能

通过离子交换的方式将Ru负载到NiFe水滑石（LDH）纳米阵列表面得到（Ru/NiFe LDH），Ru的引入显著提升了NiFe LDH的活性比表面积，暴露了更多的活性位点，同时调控了其电子结构，大大提升了其本征催化活性。在碱性条件下，催化析氢反应时仅需50 mV的过电位即可达到10 mA·cm^-2的电流密度，Tafel斜率为52.3 mV·dec^-1。而相同条件下原始NiFe LDH达到10mA·cm^-2的电流密度则需要226 mV的过电位，Tafel斜率为157.5 mV·dec^-1。同时制备的Ru/NiFe LDH也展现出了良好的析氧催化活性，在50 mA·cm^-2的电流密度下，过电位仅为231 mV，而NiFe LDH则需237 mV。Ru/NiFe LDH在长时间的电催化条件下依然能保持良好的工作稳定性。     

Photocatalytic hydrogen evolution over mesoporous TiO2/metal nanocomposites

Na⁺ complex with the dibenzo-18-crown-6 ester was used as a template to synthesize mesoporous titanium dioxide with the specific surface area 130–140 m²/g, pore diameter 5–9 nm and anatase content 70–90%. The mesoporous TiO₂ samples prepared were found to have photocatalytic activity in Cu^II, Ni^II and Ag^I reduction by aliphatic alcohols. The resulting metal–semiconductor nanostructures have remarkable photocatalytic activity in hydrogen evolution from water–alcohol mixtures, their efficiency being 50–60% greater than that of the metal-containing nano-composites based on TiO₂ Degussa P25.The effects of the thermal treatment of mesoporous TiO₂ upon its photocatalytic activity in hydrogen production were studied. The anatase content and pore size were found to be the basic parameters determining the photoreaction rate. The growth of the quantum yield of hydrogen evolution from TiO₂/Ag⁰ to TiO₂/Ni⁰ to TiO₂/Cu⁰ was interpreted in terms of differences in the electronic interaction between metal nanoparticles and the semiconductor surface. It was found that there is an optimal metal concentration range where the quantum yield of hydrogen production is maximal. A decrease in the photoreaction rate at further increment in the metal content was supposed to be connected with the enlargement of metal nanoparticles and deterioration of the intimate electron interaction between the components of the metal–semiconductor nanocomposites.     

In-situ carbonization approach for the binder-free Ir-dispersed ordered mesoporous carbon hydrogen evolution electrode

A binder-free Ir-dispersed ordered mesoporous carbon(Ir-OMC) catalytic electrode has been prepared through a designed in-situ carbonization method, which involves coating resorcinol and formaldehyde mixtures with iridium precursors onto the three-dimensional nickel foam framework, followed by insitu calcination in N_2 atmosphere at 800 ℃ for 3 h. This electrode shows a large surface area, ordered mesoporous structure and homogeneous distribution of metal nanoparticles. It presents good activity and stability towards hydrogen evolution reaction, which is attributed to the efficient mass and electron transport from the intimate contact among Ir nanoparticles, ordered mesoporous carbon matrix and 3 D conductive substrate. We hope that this in-situ carbonization synthetic route can also be applied to design more high-performance catalysts for water splitting, fuel cells and other clean energy devices.     

Hexagonal hollow mesoporous TiO2/carbon composite as an advanced anode material for lithium-ion batteries

Journal of Solid State Electrochemistry - Exploring the fast-charge anodes is crucial to meet the needs of lithium-ion battery (LIB) markets. Here, a hollow hexagonal mesoporous TiO2/carbon...     

Accelerated kinetics of alkaline hydrogen evolution/oxidation reactions on dispersed ruthenium sites through N and S dual coordination

Efficient,robust and cost-effective electrocatalysts that catalyze hydrogen evolution/oxidation reaction(HER/HOR)in alkaline media are highly demanded.Recently,single-atom catalysts(SACs)have emerged as new promising candidates;however,the rational design of supports and the optimization of coordination environment between supports and metal atoms are challenging.In this work,we successfully fabricate atomically dispersed ruthenium(Ru)species,which are strongly coordinated by N and S dual heteroatoms on holey graphene(RuSA/NSG),as an excellent bifunctional catalyst for HER/HOR.In alkaline media,the developed catalyst exhibits high catalytic performance with a low overpotential of 57.3 mV to drive a current density of 10 mA cm^-1 for HER,and its mass activity is about 5.8 times higher than that of commercial Pt/C and Ru/C catalysts at an overpotential of 100 mV.Similarly,considerable HOR performance of Ru SA/NSG is verified to be superior to Pt/C and Ru/C.Furthermore,X-ray-based spectroscopy measurements and density-functional theory calculations have confirmed that,compared with Ru–N₄,the tailored Ru–N₄–S₂ with nearby S dopants can act as more active centers to greatly accelerate the sluggish HER/HOR kinetics in alkaline media.The present work provides a new atomic-level engineering strategy to modulate catalytic activities of SACs via the coordination design using dual heteroatoms on the carbon support.     

ZnS-assisted evolution of N,S-doped hierarchical porous carbon nanofiber membrane with highly exposed Fe-N4/Cx sites for rechargeable Zn-air battery

Binder-free bifunctional electrocatalysts are attractive for rechargeable Zn-air batteries(ZABs) in gridscale energy storage and flexible electronics, but suffering from the sluggish mass transport and inadequate catalytic capability. Herein, we propose a scalable approach of in-situ engineering highly exposed Fe-N₄/Cxsites on the N,S-doped porous carbon nanofiber membrane as a binder-free air electrode catalyst for ZABs. ZnS nanospheres are firstly used as integrated structure-direct...     

Atomic-level coupled RuO2/BaRuO3 heterostructure for efficient alkaline hydrogen evolution reaction

The slow water dissociation is the rate-determining step that slows down the reaction rate in alkaline hydrogen evolution reaction(HER). Optimizing the surface electronic structure of the catalyst to lower the energy barrier of water dissociation and regulating the binding strength of adsorption intermediates are crucial strategy for boosting the catalytic performance of HER. In this study, RuO₂/BaRuO₃(RBRO)heterostructures with abundant oxygen vacancies and lattice distort...     

介孔炭的孔结构对其负载的Ru基氨合成催化剂性能的影响

采用模板法合成了介孔炭(MC),研究了其孔结构对其负载的Ru基氨合成催化剂Ba-Ru-K/MC性能的影响,采用N₂吸附脱附、扫描电镜和透射电镜等手段对介孔炭的孔结构进行了表征.研究发现,介孔炭载体的孔结构取决于模板剂的用量,当SiO₂/C质量比为1.0时,所制介孔炭比表面积最大.介孔炭负载的Ba-Ru-K催化剂活性与其介孔比表面积相关.在425℃,10MPa和10000h^-1条件下,合成氨的反应速率为139mmol/(g_cat·h).     

Improved electrochemical performance of mesoporous carbon via N/S doping

Journal of Solid State Electrochemistry - Modifying mesoporous carbon using a single additive in the form of thiourea, as a source of sulfur and nitrogen, is a flexible strategy for improving...     

Construction of Ru/WO3 with hetero-interface structure for efficient hydrogen evolution reaction

Water electrolysis is considered as one most promising technique for hydrogen production.The high efficiency electrocatalyst is the key to accelerating the sluggish kinetics of the hydrogen evolution reaction(HER) in alkaline media.In this work,an efficient HER electrocatalyst with hetero-interfacial metal-metal oxide structure was constructed through a redox solid phase reaction(SPR) strategy.During the annealing process under Ar atmosphere,RuO₂ and WS₂ in RuO₂/...     

A nano-engineered graphene/carbon nitride hybrid for photocatalytic hydrogen evolution

A metal-free photocatalytic hydrogen evolution system was successfully fabricated using heteroatom doped graphene materials as electron-transfer co-catalysts and carbon nitride as a semiconductor. The catalytic role of graphene is significantly dependent on the heteroatom dopant of the graphene, such as O, S, B, N doped/undoped graphene co-catalysts, and N-graphene shows the best catalytic hydrogen evolution rate.     

Scalable synthesis of multi-shelled hollow N-doped carbon nanosheet arrays with confined Co/CoP heterostructures from MOFs for pH-universal hydrogen evolution reaction

Developing low-cost but efficient hydrogen evolution reaction(HER)electrocatalysts over whole pH values is a significant but daunting task for the large-scale application of electrochemical hydrogen production.Herein,we develop,for the first time,a scalable MOF-assisted strategy for the fabrication and microstructural optimization of multi-shelled hollow N-doped carbon nanosheet arrays with confined Co/CoP heterostructures on carbon cloth(Co/CoP@NC/CC)for boosting HER performances.The key to this strategy is the step-by-step epitaxial growth of unprecedented multilayer ZIF-L arrays on carbon cloth,which are subsequently pyrolyzed and controllably phosphorized to achieve the precise control over the shell number and nanoarchitectures of the Co/CoP@NC/CC.Impressively,the HER performances can be significantly enhanced by increasing hollow shell number,and the optimal triple-shelled hollow Co/CoP@NC/CC exhibits low overpotentials of 86,78 and 145 mV in acidic,alkaline and neutral media to deliver a current density of 10 mA cm^-2,respectively,ranking as one of the best Co-based HER electrocatalysts over whole pH values.Further DFT calculations suggest that the Co/CoP heterostructures can effectively boost the cleavage of H–OH to generate protons and optimize the adsorption energy of hydrogen(ΔG_H*),which,together with the large electrode/electrolyte interface and accelerated charge/mass transfer of multi-shelled hollow array structure as well as the good conductivity and dispersity,are responsible for the remarkably improved HER performances.This study not only provides a new toolbox for enriching the family of multi-shelled nanoarchitecture materials,but also points out a general and effective route to develop highly efficient self-supported electrode materials for energy-related applications and beyond.