能源化学最新文献

Microbial fuel cells (MFCs) are a well-known technology used for bioelectricity production from the decomposition of organic waste via electroactive microbes. Fat, oil, and grease (FOG) as a new substrate in the anode and microalgae in the cathode were added to accelerate the electrogenesis. The effect of FOG concentrations (0.1%, 0.5%, 1%, and 1.5%) on the anode chamber was investigated. The FOG degradation, volatile fatty acid (VFAs) production, and soluble chemical oxygen demand along with voltage output kinetics were analyzed. Moreover, the microbial community analysis and active functional enzymes were also evaluated. The maximum power and current density were observed at 0.5% FOG which accounts for 96 mW m⁻² (8-folds enhancement) and 560 mA m⁻² (3.7-folds enhancement), respectively. The daily voltage output enhanced upto 2.3-folds with 77.08% coulombic efficiency under 0.5% FOG, which was the highest among all the reactors. The 0.5% FOG was degraded >85%, followed by a 1% FOG-loaded reactor. The chief enzymes in β-oxidation and electrogenesis were acetyl-CoA C-acetyltransferase, riboflavin synthase, and riboflavin kinase. The identified enzymes symbolize the presence of Clostridium sp. (>15%) and Pseudomonas (>10%) which served as electrochemical active bacteria (EAB). The major metabolic pathways involved in electrogenesis and FOG degradation were fatty acid biosynthesis and glycerophospholipid metabolism. Utilization of lipidic-waste (such as FOG) in MFCs could be a potential approach for simultaneous biowaste utilization and bioenergy generation.

Electrosynthesis of ammonia from the reduction of nitrogen is still confronted with the limited supply of gas reactant in dynamics as well as high activation barrier in thermodynamics. Unfortunately, despite tremendous efforts devoted to electrocatalysts themselves, they still fail to tackle the above two challenges simultaneously. Herein, we employ a heterogeneous catalyst adlayer—composed of crown ethers associated with Li⁺ ions—to achieve the dual promotion of dynamics and thermodynamics for ambient ammonia synthesis. Dynamically, the bound Li⁺ ions interact with the strong quadrupole moment of nitrogen, and trigger considerable reactant flux toward the catalyst. Thermodynamically, Li⁺ associated with the oxygen of crown ether achieves a higher density of states at the Fermi level for the catalyst, enabling effortless electron transfer from the catalysts to nitrogen and thus greatly reducing the activation barrier. As expected, the proof-of-concept system achieves an ammonia yield rate of 168.5 μg h⁻¹ mg⁻¹ and a Faradaic efficiency of 75.3% at −0.3 V vs. RHE. This system-level approach opens up pathways for tackling the two key challenges that have limited the field of ammonia synthesis.

Supercapacitors are promising energy storage devices in current century due to their high specific capacitance, cyclic stability, high power density, and high voltage rating. Due to their excellent electrochemical properties, supercapacitors are invariably used in a multitude of applications ranging from portable electronics to electric vehicles. The electrochemical performance of a supercapacitor mainly depends on the type of electrode-active material used in it. Thereby a careful selection is mandatory to achieve the excellency. Nanostructured electrode-active materials such as carbon nanomaterials, transition metal oxides, transition metal dichalcogenides (TMDs), electronically conducting polymers, etc. are invariably used for supercapacitor application. Among these, TMDs have received great interest, particularly transition metal disulfides such as molybdenum disulfide, tin disulfide (SnS₂), etc. Tin is abundant on the earth with excellent charge storage capabilities, attracted great scientific interest for application as electrode materials in supercapacitors. Good electronic conductivity, long cycling life and low-cost are its added advantages. Herein, we discuss the recent trends in layered two-dimensional (2D) SnS₂-based electrodes to develop low-cost supercapacitors. Initially, their crystal structure, basic properties, synthesis methods are discussed. Further, strategically designing electrode nanostructures to achieve excellent electrochemical performance is reviewed then after. This includes material design in terms of morphology, pore-size, and shape as well as preparation of 2D SnS₂-based nanocomposite electrodes. Furthermore, the challenges and future perspectives of 2D SnS₂-based supercapacitors are included.

CO₂ hydrogenation is an attractive way to store and utilize carbon dioxide generated by industrial processes, as well as to produce valuable chemicals from renewable and abundant resources. Iron catalysts are commonly used for the hydrogenation of carbon oxides to hydrocarbons. Iron-molybdenum catalysts have found numerous applications in catalysis, but have been never evaluated in the CO₂ hydrogenation. In this work, the structural properties of iron-molybdenum catalysts without and with a promoting alkali metal (Li, Na, K, Rb, or Cs) were characterized using X-ray diffraction, hydrogen temperature-programmed reduction, CO₂ temperature-programmed desorption, in-situ ⁵⁷Fe Mossbauer spectroscopy and operando X-ray adsorption spectroscopy. Their catalytic performance was evaluated in the CO₂ hydrogenation. During the reaction conditions, the catalysts undergo the formation of an iron (II) molybdate structure, accompanied by a partial reduction of molybdenum and carbidization of iron. The rate of CO₂ conversion and product selectivity strongly depend on the promoting alkali metals, and electronegativity was identified as an important factor affecting the catalytic performance. Higher CO₂ conversion rates were observed with the promoters having higher electronegativity, while low electronegativity of alkali metals favors higher light olefin selectivity.

Undoped nickel-based catalysts supported on depleted uranium oxide allow one to carry out CO₂ methanation process under extremely low reaction temperature under atmospheric pressure and powered by a contactless induction heating. By adjusting the reaction conditions, the catalyst is able to perform CO₂ methanation reaction under autothermal process operated inside a non-adiabatic reactor, without any external energy supply. Such autothermal process is possible thanks to the high apparent density of the UO_x which allows one to confine the reaction heat in a small catalyst volume in order to confine the exothermicity of the reaction inside the catalyst and to operate the reaction at equilibrium heat in-heat out. Such autothermal operation mode allows one to significantly reduce the complexity of the process compared to that operated using adiabatic reactor, where complete insulation is required to prevent heat disequilibrium, in order to reduce as much as possible, the heat exchange with the external medium. The catalyst displays an extremely high stability as a function of time on stream as no apparent deactivation. It is expected that such new catalyst with unprecedented catalytic performance could open new era in the field of heterogeneous catalysis where traditional supports show their limitations to operate catalytic processes under severe reaction conditions.

The supercapacitor electrode materials suffer from structure pulverization and sluggish electrode kinetics under high current rates. Herein, a unique NiMoO₄@Co-B heterostructure composed of highly conductive Co-B nanoflakes and a semiconductive NiMoO₄ nanorod is designed as an electrode material to exert the energy storage effect on supercapacitors. The formed Mott-Schottky heterostructure is helpful to overcome the ion diffusion barrier and charge transfer resistance during charging and discharging. Moreover, this crystalline-amorphous heterogeneous phase could provide additional ion storage sites and better strain adaptability. Remarkably, the optimized NiMoO₄@Co-B hierarchical nanorods (the mass ratio of NiMoO₄/Co-B is 3:1) present greatly enhanced electrochemical characteristics compared with other components, and show superior specific capacity of 236.2 mA h g⁻¹ at the current density of 0.5 A g⁻¹, as well as remarked rate capability. The present work broadens the horizons of advanced electrode design with distinct heterogeneous interface in other energy storage and conversion field.

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 conductive support, oxyphilic MoSe₂, and Ru active sites imparted a strong synergistic effect and charge redistribution in the Ru periphery which induced high catalytic activity, stability, and kinetics for HER. Specifically, the obtained Ru/MoSe₂@MHCS required a small overpotential of 25.5 and 38.4 mV to drive the kinetic current density of 10 mA cm⁻² both in acid and alkaline media, respectively, which was comparable to that of the Pt/C catalyst. Experimental and theoretical results demonstrated that the charge transfer from MoSe₂ to Ru NPs enriched the electronic density of Ru sites and thus facilitated hydrogen adsorption and water dissociation. The current work showed the significant interfacial engineering in Ru-based catalysts development and catalysis promotion effect understanding via the metal-support interaction.

Borocarbonitride (BCN) materials are newly developed metal-free catalytic materials exhibiting high selectivity in oxidative dehydrogenation (ODH) of alkanes. However, the in-depth understandings on the role of boron (B) dopants and the intrinsic activities of –C=O and –B–OH still remain unknown. Herein, we report a series of BCN materials with regulable B content and surface oxygen functional groups via self-assembly and pyrolysis of guanine and boric acid. We found that the B/C ratio is the key parameter to determine the activity of ODH and product distribution. Among them, the high ethylbenzene conversion (∼57%) and styrene selectivity (∼83%) are achieved in ODH for B₁CN. The styrene selectivity can be improved by increasing of B/C ratio and this value reaches near 100% for B₅CN. Structural characterizations and kinetic measurements indicate that –C=O and –B–OH dual sites on BCN are real active sites of ODH reaction. The intrinsic activity of –C=O (5.556 × 10⁻⁴ s⁻¹) is found to be 23.7 times higher than –B–OH (0.234 × 10⁻⁴ s⁻¹) site. More importantly, we reveal that the deep oxidation to undesirable CO₂ occurs on –C=O rather than –B–OH site, and B dopant in BCN materials can reduce the nucleophilicity of –C=O site to eliminate the CO₂ emission. Overall, the present work provides a new insight on the structure–function relationship of the BCN catalytic systems.

The direct oxidation of nitrogen is a potential pathway to achieving the zero-carbon-emission synthesis of nitric acid or nitrate, because it does not involve ammonia synthesis and additional ammonia oxidation processes. However, the slow kinetics of nitrogen oxidation and the difficult selective control of oxidation products hinder the development of this process. In this study, a plasma-driven gas-liquid relay reaction system was developed to overcome these limitations. A typical feature of this reaction system is that it can efficiently generate NO_x under plasma exposure; moreover, the specific anions in the absorption solution can be oxidized to strong oxidants capable of relay oxidation of low-valence nitrogen oxides. This feature allows for the deep oxidation of nitrogen, thus enabling the oxidation products of nitrogen to exist in high-valence states in the absorption solution. For experimental verification, we achieved the 100% selective synthesis of nitrate under plasma exposure, with air as the supply gas and a sodium sulfate solution as the absorption solution.

Water electrolysis using proton-exchange membranes is one of the most promising technologies for carbon-neutral and sustainable energy production. Generally, the overall efficiency of water splitting is limited by the oxygen evolution reaction (OER). Nevertheless, a trade-off between activity and stability exists for most electrocatalytic materials in strong acids and oxidizing media, and the development of efficient and stable catalytic materials has been an important focus of research. In this view, gaining in-depth insights into the OER system, particularly the interactions between reaction intermediates and active sites, is significantly important. To this end, this review introduces the fundamentals of the OER over Ru-based materials, including the conventional adsorbate evolution mechanism, lattice oxygen oxidation mechanism, and oxide path mechanism. Moreover, the up-to-date progress of representative modifications for improving OER performance is further discussed with reference to specific mechanisms, such as tuning of geometric, electronic structures, incorporation of proton acceptors, and optimization of metal-oxygen covalency. Finally, some valuable insights into the challenges and opportunities for OER electrocatalysts are provided with the aim to promote the development of next-generation catalysts with high activity and excellent stability.