Transition metal dichalcogenide materials have been explored extensively as catalysts to negotiate the hydrogen evolution reaction, but they often run at a large excess thermodynamic cost. Although ...activating strategies, such as defects and composition engineering, have led to remarkable activity gains, there remains the requirement for better performance that aims for real device applications. We report here a phosphorus-doping-induced phase transition from cubic to orthorhombic phases in CoSe
. It has been found that the achieved orthorhombic CoSe
with appropriate phosphorus dopant (8 wt%) needs the lowest overpotential of 104 mV at 10 mA cm
in 1 M KOH, with onset potential as small as -31 mV. This catalyst demonstrates negligible activity decay after 20 h of operation. The striking catalysis performance can be attributed to the favorable electronic structure and local coordination environment created by this doping-induced structural phase transition strategy.
Electrochemical conversion of CO2 to value‐added chemicals using renewable electricity provides a promising way to mitigate both global warming and the energy crisis. Here, a facile ion‐adsorption ...strategy is reported to construct highly active graphene‐based catalysts for CO2 reduction to CO. The isolated transition metal cyclam‐like moieties formed upon ion adsorption are found to contribute to the observed improvements. Free from the conventional harsh pyrolysis and acid‐leaching procedures, this solution‐chemistry strategy is easy to scale up and of general applicability, thus paving a rational avenue for the design of high‐efficiency catalysts for CO2 reduction and beyond.
A feasible ion‐adsorption strategy is highlighted to bring unprecedentedly efficient and selective CO2 reduction activity to nitrogen‐doped graphene. Free from high‐temperature pyrolysis and acid leaching, this solution‐chemistry route incorporating molecular‐catalyst moieties into a highly conductive carbon matrix provides a practical approach to design high‐efficiency electrocatalysts for CO2 reduction and related catalytic reactions.
Recent years have witnessed the rise of graphene and its applications in various electronic devices. Specifically, featuring excellent flexibility, transparency, conductivity, and mechanical ...robustness, graphene has emerged as a versatile material for flexible electronics. In the past decade, facilitated by various laser processing technologies, including the laser‐treatment‐induced photoreduction of graphene oxides, flexible patterning, hierarchical structuring, heteroatom doping, controllable thinning, etching, and shock of graphene, along with laser‐induced graphene on polyimide, graphene has found broad applications in a wide range of electronic devices, such as power generators, supercapacitors, optoelectronic devices, sensors, and actuators. Here, the recent advancements in the laser fabrication of graphene‐based flexible electronic devices are comprehensively summarized. The various laser fabrication technologies that have been employed for the preparation, processing, and modification of graphene and its derivatives are reviewed. A thorough overview of typical laser‐enabled flexible electronic devices that are based on various graphene sources is presented. With the rapid progress that has been made in the research on graphene preparation methodologies and laser micronanofabrication technologies, graphene‐based electronics may soon undergo fast development.
Recent advancements in the laser fabrication of graphene‐based flexible electronic devices are comprehensively reviewed. Various laser processing technologies that enable preparation, processing, and modification of graphene and its derivatives are summarized. An overview of typical laser‐fabricated flexible electronic devices based on graphene‐related materials is presented.
The design of active, selective, and stable CO2 reduction electrocatalysts is still challenging. A series of atomically dispersed Co catalysts with different nitrogen coordination numbers were ...prepared and their CO2 electroreduction catalytic performance was explored. The best catalyst, atomically dispersed Co with two‐coordinate nitrogen atoms, achieves both high selectivity and superior activity with 94 % CO formation Faradaic efficiency and a current density of 18.1 mA cm−2 at an overpotential of 520 mV. The CO formation turnover frequency reaches a record value of 18 200 h−1, surpassing most reported metal‐based catalysts under comparable conditions. Our experimental and theoretical results demonstrate that lower a coordination number facilitates activation of CO2 to the CO2.− intermediate and hence enhances CO2 electroreduction activity.
A remarkable carbon dioxide electroreduction catalytic performance with superior activity and high selectivity was achieved on atomically dispersed Co sites through coordination environment regulating. First step in picture: C–N fragments, 1000 °C; second step: NH3 treatment.
CeO2 nanocubes (c-CeO2), nanoparticles (p-CeO2), and nanorods calcined at 500 °C (r-CeO2-500) and 700 °C (r-CeO2-700) were used as supports to synthesize a series of Ni/CeO2 catalysts for the propane ...combustion and oxidative dehydrogenation of propane (ODHP) reactions. The Ni-CeO2 interaction greatly promotes the reducibility of CeO2, but CeO2 morphology-dependent Ni-CeO2 interaction was observed to form different speciation of Ni species (Ni2+ dissolved in CeO2, highly dispersive NiO, NiO aggregate) and oxygen species (strongly activated oxygen species, medially activated oxygen species, weakly activated oxygen species) in various Ni/CeO2 catalysts. Ni-CeO2 interaction is stronger in Ni/c-CeO2 catalysts than in other Ni/CeO2 catalysts. Different morphology-dependences of Ni/CeO2 catalysts in propane combustion and ODHP reactions were observed. The Ni/r-CeO2-500 catalyst with the largest strongly activated oxygen species is most catalytic active in the propane combustion reaction while the Ni/c-CeO2 catalyst with the largest amount of weakly activated oxygen species exhibits the best catalytic performance in the ODHP reaction. Thus, the CeO2 morphology engineering strategy is effective in finely tuning the metal-CeO2 interaction and the reactivity of oxygen species to meet the requirements of different types of catalytic oxidation reactions.
Soft open points (SOPs) are power electronic devices that may replace conventional normally-open points in distribution networks. They can be used for active power flow control, reactive power ...compensation, fault isolation, and service restoration through network reconfiguration with enhanced operation flexibility and grid resiliency. Due to unbalanced loading conditions, the voltage unbalance issue, as a common problem in distribution networks, has negative impacts on distribution network operation. In this paper, a control strategy of voltage unbalance compensation for feeders using SOPs is proposed. With the power flow control, three-phase current is regulated simultaneously to mitigate the unbalanced voltage between neighboring feeders where SOPs are installed. Feeder voltage unbalance and current unbalance among three phases are compensated with the injection of negative-sequence and zero-sequence current from SOPs. Especially in response to power outages, three-phase voltage of isolated loads is regulated to be balanced by the control of SOPs connected to the feeders under faults, even if the loads are unbalanced. A MATLAB/Simulink model of the IEEE 13-bus test feeder with an SOP across feeder ends is implemented, and experimental tests on a hardware-in-the-loop platform are implemented to validate the effectiveness of the proposed control strategy.
Supported Pd catalysts are active in catalyzing the highly exothermic methane combustion reaction but tend to be deactivated owing to local hyperthermal environments. Herein we report an effective ...approach to stabilize Pd/SiO2 catalysts with porous Al2O3 overlayers coated by atomic layer deposition (ALD). 27Al magic angle spinning NMR analysis showed that Al2O3 overlayers on Pd particles coated by the ALD method are rich in pentacoordinated Al3+ sites capable of strongly interacting with adjacent surface PdOx phases on supported Pd particles. Consequently, Al2O3‐decorated Pd/SiO2 catalysts exhibit active and stable PdOx and Pd–PdOx structures to efficiently catalyze methane combustion between 200 and 850 °C. These results reveal the unique structural characteristics of Al2O3 overlayers on metal surfaces coated by the ALD method and provide a practical strategy to explore stable and efficient supported Pd catalysts for methane combustion.
Staying active: Al2O3 overlayers on Pd particles coated by atomic layer disposition were rich in pentacoordinated Al3+ sites capable of strongly interacting with adjacent surface PdOx phases on supported Pd particles. The resulting active and stable PdOx and Pd–PdOx structures catalyzed methane combustion efficiently between 200 and 850 °C (see picture; o‐Pd/SiO2‐T denotes the supported catalyst comprising Pd octahedra on SiO2 nanospheres).
Developing a facile route to access active and well-defined single atom sites catalysts has been a major area of focus for single atoms catalysts (SACs). Herein, we demonstrate a simple approach to ...generate atomically dispersed platinum via a thermal emitting method using bulk Pt metal as a precursor, significantly simplifying synthesis routes and minimizing synthesis costs. The ammonia produced by pyrolysis of Dicyandiamide can coordinate with platinum atoms by strong coordination effect. Then, the volatile Pt(NH3) x can be anchored onto the surface of defective graphene. The as-prepared Pt SAs/DG exhibits high activity for the electrochemical hydrogen evolution reaction and selective oxidation of various organosilanes. This viable thermal emitting strategy can also be applied to other single metal atoms, for example, gold and palladium. Our findings provide an enabling and versatile platform for facile accessing SACs toward many industrial important reactions.
The interaction of hydrogen with reduced ceria (CeO2−x) powders and CeO2−x(111) thin films was studied using several characterization techniques including TEM, XRD, LEED, XPS, RPES, EELS, ESR, and ...TDS. The results clearly indicate that both in reduced ceria powders as well as in reduced single crystal ceria films hydrogen may form hydroxyls at the surface and hydride species below the surface. The formation of hydrides is clearly linked to the presence of oxygen vacancies and is accompanied by the transfer of an electron from a Ce3+ species to hydrogen, which results in the formation of Ce4+, and thus in oxidation of ceria.
Oxidizing hydride: The incorporation of hydride species into reduced ceria causes oxidation of the oxide. Accompanying changes in the electronic structure of the oxide are investigated, as well as the thermal stability of the hydride species.
Abstract Cu–ZnO–Al 2 O 3 catalysts are used as the industrial catalysts for water gas shift (WGS) and CO hydrogenation to methanol reactions. Herein, via a comprehensive experimental and theoretical ...calculation study of a series of ZnO/Cu nanocrystals inverse catalysts with well-defined Cu structures, we report that the ZnO–Cu catalysts undergo Cu structure-dependent and reaction-sensitive in situ restructuring during WGS and CO hydrogenation reactions under typical reaction conditions, forming the active sites of Cu Cu(100) -hydroxylated ZnO ensemble and Cu Cu(611) Zn alloy, respectively. These results provide insights into the active sites of Cu–ZnO catalysts for the WGS and CO hydrogenation reactions and reveal the Cu structural effects, and offer the feasible guideline for optimizing the structures of Cu–ZnO–Al 2 O 3 catalysts.
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