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The oxygen evolution reactions in acid play an important role in multiple energy storage devices. The practical promising Ru-Ir based catalysts need both the stable high oxidation state of the Ru centers and the high stability of these Ru species. Here, we report stable and oxidative charged Ru in two-dimensional ruthenium-iridium oxide enhances the activity. The Ru 0.5 Ir 0.5 O 2 catalyst shows high activity in acid with a low overpotential of 151 mV at 10 mA cm −2 , a high turnover frequency of 6.84 s −1 at 1.44 V versus reversible hydrogen electrode and good stability (618.3 h operation). Ru 0.5 Ir 0.5 O 2 catalysts can form more Ru active sites with high oxidation states at lower applied voltages after Ir incorporation, which is confirmed by the pulse voltage induced current method. Also, The X-ray absorption spectroscopy data shows that the Ru-O-Ir local structure in two-dimensional Ru 0.5 Ir 0.5 O 2 solid solution improved the stability of these Ru centers. Stabilizing high oxidation state of Ru centers is important to achieve stable performance for acidic oxygen evolution reaction. Here the authors report two-dimensional ruthenium-iridium oxide for enhanced stability and activity for acidic water oxidation in proton exchange membrane electrolyzer.

The energy crisis has always been a widely concerned problem. It is an urgent need for green and renewable energy technologies to achieve sustainable development, and the photo-assisted charging energy storage devices provide a new way to realize the sustainable utilization of solar energy. Here, we fabricated a photo-assisted charging fibrous supercapacitor (NM 2 P 1 ) with Ti 3 C 2 T x -based hybrid fibre modified by nitrogen-doped carbon dots (NCDs). The NM 2 P 1 fibre provides a volumetric capacitance of 1,445 F·cm −3 (630 F·g −1 ) at 10 A·cm −3 under photo-assisted charging, which increases by 35.9% than that of dark condition (1,063 F·cm −3 /464 F·g −1 ). Furthermore, the NM 2 P 1 fibrous supercapacitor device shows that the maximum volumetric energy density and volumetric power density are 18.75 mWh·cm −3 and 8,382 mW·cm −3 . Notably, the transient photovoltage (TPV) test was used to further confirm that NCDs as a photosensitizer enhance the light absorption capacity and faster charge transfer kinetics of NM 2 P 1 fibre. This work directly exploits solar energy to improve the overall performance of supercapacitor, which opens up opportunities for the utilization of renewable energy and the development of photosensitive energy equipment.

The coupled green energy and chemical production by photocatalysis represents a promising sustainable pathway, which poses great challenges for the multifunction integration of catalytic systems. Here we show a promising green photocatalyst design using Cu-ZnIn 2 S 4 nanosheets and carbon dots as building units, which enables the integration of reaction, mass transfer, and separation functions in the nano-space, mimicking a nanoreactor. This function integration results in great activity promotion for benzyl alcohol oxidation coupled H 2 production, with H 2 /benzaldehyde production rates of 45.95/46.47 mmol g −1  h −1 , 36.87 and 36.73 times to pure ZnIn 2 S 4 , respectively, owning to the enhanced charge accumulation and mass transfer according to in-situ spectroscopies and computational simulations of the built-in electrical field. Near-unity selectivity of benzaldehyde is achieved via the effective separation enabled by the Cu(II)-mediated conformation flipping of the intermediates and subsequent π-π conjugation. This work demonstrates an inspiring proof-of-concept nanoreactor design of photocatalysts for coupled sustainable systems. Cu-doped ZnIn 2 S 4 nanosheets decorated with carbon dots are reported for the photocatalytic oxidation of organic alcohols coupled with H 2 evolution with enhanced yields due to efficient charge accumulation and mass transfer at the catalyst surface.

Syngas, a CO and H 2 mixture mostly generated from non-renewable fossil fuels, is an essential feedstock for production of liquid fuels. Electrochemical reduction of CO 2 and H + /H 2 O is an alternative renewable route to produce syngas. Here we introduce the concept of coupling a hydrogen evolution reaction (HER) catalyst with a CDots/C 3 N 4 composite (a CO 2 reduction catalyst) to achieve a cheap, stable, selective and efficient route for tunable syngas production. Co 3 O 4 , MoS 2 , Au and Pt serve as the HER component. The Co 3 O 4 -CDots-C 3 N 4 electrocatalyst is found to be the most efficient among the combinations studied. The H 2 /CO ratio of the produced syngas is tunable from 0.07:1 to 4:1 by controlling the potential. This catalyst is highly stable for syngas generation (over 100 h) with no other products besides CO and H 2 . Insight into the mechanisms balancing between CO 2 reduction and H 2 evolution when applying the HER-CDots-C 3 N 4 catalyst concept is provided. Simultaneous electrochemical reduction of CO 2 and H + /H 2 O is an attractive renewable route to produce syngas mixtures. Here, the authors introduce a ternary Co 3 O 4 -CDots-C 3 N 4 electrocatalyst that couples hydrogen evolution and CO 2 reduction catalysts and achieves cheap, stable and tunable production of syngas.

Highly efficient photo-assisted electrocatalysis for methanol oxidation reaction (MOR) realizes the conversion of solar and chemical energy into electric energy simultaneously. Here we report a Pt-MXene-TiO 2 composite for highly efficient MOR via a photoactive cascaded electro-catalytic process. With light (UV and visible light) irradiation, MXene-TiO 2 serves as the photo active centre (photoinduced hole) to activate the methanol molecules, while Pt particles are the active centre for the following electro-catalytic oxidation of those activated methanol molecules. Pt-MXene-TiO 2 catalyst exhibits a lower onset potential (0.33 V) and an impressive mass activity of 2,750.42 mA·mg −1 Pt under light illumination. It represents the highest MOR activity ever reported for photo-assisted electrocatalysts. Pt-MXene-TiO 2 also shows excellent CO tolerance ability and stability, in which, after long-term (5,000 s) reaction, still keeps a high mass activity of 1,269.81 mA·mg −1 Pt (62.66% of its initial activity). The photo-electro-catalytic system proposed in this work offers novel opportunities for exploiting photo-assisted enhancement of highly efficient and stable catalysts for MOR.

High-voltage direct current (HVDC) cables are essential for long-distance power transmission, particularly in renewable energy applications. Cross-linked polyethylene (XLPE) insulation is commonly used in these cables, but protrusion defects that occur during manufacturing can distort the electric field and initiate partial discharge (PD), accelerating insulation degradation. In this study, partial discharge experiments were conducted at 50 °C and 80 kV to investigate the behavior of internal semi-conductive protrusion defects in insulation, following methodologies aligned with relevant industry standards IEC 60270 for partial discharge measurements. This voltage condition is obtained from the previous pre-test using the same model, and can ensure that the cable can generate partial discharge under the conditions of 50°C and 80kV, but there will be no rapid deterioration of the cable leading to breakdown, which meets the needs of this experiment. The discharge process is divided into stages, and the relationship between discharge frequency, quantity, and cumulative discharge is explored. The results reveal a clear increase in discharge activity, especially in the fourth stage, which corresponds to the accelerated development of the discharge channel and impending insulation breakdown. These findings provide valuable insights into the defect’s progression and highlight the risks of protrusion defects in HVDC cable insulation. This research contributes to the understanding of insulation degradation mechanisms and offers important data for improving the design, manufacturing, and maintenance of HVDC cables.

The 2011 Fukushima accident highlighted the vulnerability of traditional Zr alloy fuel cladding under loss-of-coolant accident (LOCA) conditions, prompting the development of accident-tolerant fuel (ATF) systems. A promising near-term solution involves depositing protective coatings on existing Zr alloy cladding. Among various deposition techniques, cold spray technology has emerged as one of the leading methods due to its solid-state, low-temperature process, which minimises thermal degradation and allows for the deposition of a wide range of high-performance materials. This review provides a comprehensive examination of recent advances in cold-sprayed coatings for ATF cladding, beginning with an overview of the fundamentals of cold spray technology and its specific advantages for nuclear applications. The core of the review critically analyses three primary coating systems: Cr, FeCrAl alloys, and MAX phase composites, with a particular focus on Cr coatings, as they have been more extensively studied compared to the other two material systems. Key coating properties, including microstructure of the coating-substrate interface, mechanical properties, thermal conductivity, oxidation resistance, irradiation tolerance, and performance under normal operation and simulated LOCA conditions, are discussed in detail, with particular emphasis on the potential of cold-sprayed Cr coatings to enhance Zr alloy cladding. Cr coatings demonstrate significant improvements in oxidation resistance and irradiation stability, but also face challenges such as high-temperature interfacial reactions. To address these issues, promising solutions, such as diffusion-barrier bilayer systems, are being explored. Additionally, the review discusses FeCrAl and MAX phase composite coatings, highlighting their promising long-term performance under extreme conditions. The review concludes with recommendations for further research to optimise cold spray processes and ensure the robustness of coatings in operational reactor environments.

Carbon dots (CDs), as a unique zero-dimensional member of carbon materials, have attracted numerous attentions for their potential applications in optoelectronic, biological, and energy related fields. Recently, CDs as catalysts for energy conversion reactions under multi-physical conditions such as light and/or electricity have grown into a research frontier due to their advantages of high visible light utilization, fast migration of charge carriers, efficient surface redox reactions and good electrical conductivity. In this review, we summarize the fabrication methods of CDs and corresponding CD nanocomposites, including the strategies of surface modification and heteroatom doping. The properties of CDs that concerned to the photo- and electro-catalysis are highlighted and detailed corresponding applications are listed. More importantly, as new non-contact detection technologies, transient photo-induced voltage/current have been developed to detect and study the charge transfer kinetics, which can sensitively reflect the complex electron separation and transfer behavior in photo-/electro-catalysts. The development and application of the techniques are reviewed. Finally, we discuss and outline the major challenges and opportunities for future CD-based catalysts, and the needs and expectations for the development of novel characterization technologies. We briefly introduce basic properties and photoelectric functional unit characteristics of CDs recently. The application of CDs recently in photoelectrocatalytic field is briefly summarized. Applications of new in-situ characterization techniques (TPC/TPV) are introduced.

Carbon emission reduction is an important goal of China’s sustainable economic development. As a new urbanization construction model, the importance of smart city construction for economic growth and innovation is recognized by the academic community. The impact of smart cities on the environment, especially on carbon emission reductions, has yet to be verified. This has implications for the green and low-carbon transformation of China, the realization of the peak carbon and carbon neutrality goals and the effectiveness of smart city pilot policies. For these reasons, this paper utilizes China’s urban panel data, and using the difference-in-difference method, investigates the smart city pilot policy as a quasi-natural experiment of new urbanization construction and its impact on urban carbon emission reductions. The results are summarized as follows: (1) Smart city construction has reduced the carbon emissions of pilot cities by about 4.36% compared with non-pilot cities. (2) The dynamic impact analysis found that the carbon emission reduction effect of smart city construction tends not to be effective until the third year of the implementation of the policy, that the policy effect gradually increases over time, and that its carbon emission reduction dividend has a long-term sustainability. (3) The analysis of the influence mechanisms determined that smart city construction mainly promotes urban carbon emission reduction through three paths, including improving technology innovation capacity, enhancing the attraction of foreign direct investment, and accelerating the upgrading of industrial structure. (4) The heterogeneity analysis indicates that smart city construction has stronger carbon emission reduction effects in the “two control zones”, non-old industrial bases and non-resource-based cities.

The Isothermal Relaxation Current (IRC) method, as a non-destructive condition evaluation method based on insulation dielectric response, has been applied in the maintenance of power cables. However, the relaxation current is usually conducted through the outer shield of the high-voltage wire, which will introduce the extra depolarization current into the test circuit, affecting the accuracy of the test results. Furthermore, most IRC cable measurements are single-phase, which means depolarization currents are measured for each cable separately. In order to improve the measurement accuracy and efficiency of the IRC test, this paper proposes an improved IRC measurement method based on an isolated circuit, which discharges the interference current from the high-voltage insulated wire back to the earth and reduces the measurement error of depolarization current. At the same time, a three-phase IRC simultaneous test system is designed, and the control software is developed. Furthermore, by verifying the accuracy of the test system, the independence of the single-phase circuit and the consistency of the three-phase circuit is achieved. The effect of depolarization time and temperature on the relaxation current is then explored to determine the suitable parameter of the IRC test. Finally, the IRC system is used to evaluate the aging state of 10 kV cables with various aging conditions in the air and water for the longest 12 months. Critical parameters such as aging factor and time constants are compared to investigate the aging characteristics of tested cables with various aging conditions in the air and water. The proposed method and research conclusions can provide helpful references for the non-destructive condition evaluation for high-voltage cable insulation.