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The surface electron density significantly affects the photocatalytic efficiency, especially the photocatalytic CO 2 reduction reaction, which involves multi-electron participation in the conversion process. Herein, we propose a conceptually different mechanism for surface electron density modulation based on the model of Au anchored CdS. We firstly manipulate the direction of electron transfer by regulating the vacancy types of CdS. When electrons accumulate on vacancies instead of single Au atoms, the adsorption types of CO 2 change from physical adsorption to chemical adsorption. More importantly, the surface electron density is manipulated by controlling the size of Au nanostructures. When Au nanoclusters downsize to single Au atoms, the strong hybridization of Au 5 d and S 2 p orbits accelerates the photo-electrons transfer onto the surface, resulting in more electrons available for CO 2 reduction. As a result, the product generation rate of Au SA /Cd 1−x S manifests a remarkable at least 113-fold enhancement compared with pristine Cd 1−x S. The electron density of reactive sites significantly affects catalytic performances. Here, authors demonstrate the electron density of different reactive sites can be modulated by regulating the type of vacancy and the size of Au, leading to effective CO 2 photoreduction.

Methane dry reforming not only utilizes two potent greenhouse gases of methane and carbon dioxide, but also provides a valuable feedstock for the production of chemicals. However, this process has been heavily hindered by high operating temperature and coke formation with catalyst deactivation over the last century. Herein, we propose an approach whereby concentrated-solar catalytic methane dry reforming addresses these longstanding issues. By leveraging focused light as the sole energy source and utilizing a well-designed catalyst, the catalyst with Ni-O 4 coordination active center achieves high conversion rates of 93.6% for CH 4 and 93.7% for CO 2 , meanwhile sustaining stability for over 800 hours. Particularly noteworthy is the light-to-chemical energy conversion efficiency reaching 25.9%. This research represents a significant leap forward in integrating renewable energy sources with chemical production, offering a viable and sustainable alternative to traditional thermochemical processes for generating valuable chemicals. Dry reforming of methane (DRM) supports the circular economy and energy sustainability, yet its application is limited by high operating temperatures and coke formation. Here, the authors introduce a concentrated-solar catalytic DRM strategy that overcomes these challenges.

The polyol oxidation to dicarboxylic acid, a crucial value-accretive reaction, is still challenging due to the paradoxical relationship between efficient activation of C-H bond and rapid desorption of carboxylic acid. Herein, we break this contradiction by constructing fully exposed Pt n cluster supported on hydroxyapatite (Pt n /HAP) to promote two primary hydroxyl groups of polyol oxidation to dicarboxylic acid. Such fully exposed Pt n cluster with an average Pt-Pt coordination number of ∼3.4 exhibits unique electronic properties between Pt 1 single atom and nanoparticle Pt p . Specifically, gradient charge distribution in fully exposed Pt n cluster shows a special synergistic effect in the C-H bond activation. Moreover, the d-band centre of fully exposed Pt n cluster moderately far from the Fermi level weakens the adsorption of C = O bond in dicarboxylic acid product. As a result, fully exposed Pt n /HAP with better catalytic activity (turnover frequency: 619.1 h − 1 ) shows nearly 10 times and 1.5 times of tartronic acid selectivity than Pt 1 single atom and nanoparticle Pt p catalysts, respectively. The system is also applicable to other polyol oxidation to dicarboxylic acids with noteworthy catalytic results. Polyol oxidation to dicarboxylic acids is hindered by conflicting needs for C–H activation and product desorption. This work resolves the issue using fully exposed Ptn clusters on hydroxyapatite, enabling efficient and selective catalysis.

BiOCl has been used in the photoreduction of CO 2 , but exhibits limited photocatalytic activity. In this study, Bi was in situ reduced and deposited on the surface of (001)-dominated BiOCl nanosheets by NaBH 4 to form Bi/BiOCl nanosheets enriched with oxygen vacancies. The as-prepared Bi/BiOCl nanosheets having low thickness (ca. 10 nm) showed much higher concentration of oxygen vacancies compared to Bi/BiOCl nanoplates having high thickness (ca. 100 nm). Subsequently, the photocatalytic activity of the Bi/BiOCl nanosheets enriched with oxygen vacancies for CO 2 reduction was dramatically enhanced and much higher than that of BiOCl nanoplates, nanosheets, and Bi/BiOCl nanoplates. It showed that the improved photocatalytic activity in the reduction of CO 2 can be attributed to the enhanced separation efficiency of photogenerated electron–hole pairs of the oxygen vacancies on BiOCl nanosheets and Bi metals. This work demonstrated that the in situ reduction of non-noble metals on the surface of BiOCl nanosheets that are enriched with oxygen vacancies is favorable for increasing photocatalytic CO 2 reduction.

High-speed railway catenaries are vital components in railway traction power supply systems. To ensure stable contact between the pantograph and the catenary, droppers are positioned between the messenger wire and contact line. The failure of one or more droppers will affect the power supply of the catenary and the operation of the railway. In this paper, we modify the You Only Look Once version five (YOLOv5) model in several ways and propose a method for improving the identification of dropper status and the detection of small defects. Firstly, to focus on small target features, the selective kernel attention module is added to the backbone. Secondly, the feature graphs of different scales extracted from the backbone network are fed into the bidirectional feature pyramid network for multiscale feature fusion. Thirdly, the YOLO head is replaced by a decoupled head to improve the convergence speed and detection accuracy of the model. The experimental results show that the proposed model achieves a mean average precision of 92.9% on the dropper dataset, an increase of 3.8% over the results using YOLOv5s. The detection accuracy of small dropper defects reaches 79.2%, representing an increase of 10.8% compared with YOLOv5s and demonstrating that our model is better at detecting small defects.

Optimizing travel routes in urban transportation networks is essential for enhancing traffic efficiency in major cities. This study focuses on optimizing the combined subway and taxi travel routes from Beijing Union University to Beijing South Railway Station, a critical route for students and staff in Beijing. To address this, we propose three genetic algorithms: the Standard Genetic Algorithm (SGA), the Multipoint Crossover and Elitist Selection Genetic Algorithm (MPEGA), and the Improved Dynamic Crossover and Mutation Rate Genetic Algorithm (IDCMGA). Experimental results indicate that MPEGA reduces the mean travel cost by 15.21%, the variance by 81.72%, and the standard deviation by 57.25% compared to SGA. Additionally, IDCMGA reduces the average by 1.76%, the variance by 63.16%, and the standard deviation by 39.30% compared to MPEGA. The improved IDCMGA algorithm demonstrates significant advantages over the other two algorithms in terms of global optimization capability, convergence speed, and stability, and is more adept at adapting to new traffic conditions to identify the optimal route. Optimizing this route not only reduces commuting time and costs but also alleviates traffic congestion, thereby enhancing the overall efficiency of the urban transportation system.

Common studies on entangled metallic wire material (EMWM) lack exploration of the material’s electrical conductivity. This paper focuses on the dynamic mechanical properties, electrical conductivity and fatigue properties of Beryllium bronze alloy wrapped wire material (QBe2-EMWM) with excellent electrical conductivity. Three batches of 304-EMWM and QBe2-EMWM with different densities are tested under cyclic dynamic loading, and average dynamic stiffness, loss factor, and resistance are calculated. The experimental results show that the dynamic mechanical properties and electrical conductivity of EMWM are significantly affected by the density of EMWM. The loss factor of EMWM increases with the increase of excitation frequency and excitation amplitude, while the average dynamic stiffness is the opposite. The resistance of QBe2-EMWM is only 5% of that of 304-EMWM. Furthermore, an EMWM fatigue life assessment method based on damage factors is proposed. The fatigue life of EMWM is determined by considering the damage trend of average dynamic stiffness, loss factor, and resistance. The stiffness and resistance of EMWM increase with the increase of excitation times, while the loss factor is the opposite. When the number of excitations reaches a certain value, the mechanical and electrical indexes of EMWM is regionally stable. SEM observations show that the failure modes of 304-EMWM are frictional wear and friction debris, while the failure modes of QBe2-EMWM are indentation, friction debris, frictional wear, and fracture. The cumulative damage model is established, and the rationality of the model is verified by experimental data.

Methane is the fundamental raw material of the C1 chemical industry, with abundant reserves. Its direct conversion into high-value-added chemicals has great scientific significance and broad commercial potential for the efficient use of methane resources. However, it is difficult to convert methane into more useful hydrocarbons and hydrogen, as the reaction usually requires external energy to overcome thermodynamic limitations. Non-oxidative coupling of methane to produce ethane and hydrogen is a promising supply technology. Catalysts which can be adapted to various energy sources are key to this technology. In recent years, considerable progress has been made in the design and application of these thermal and photocatalysts. This review outlines some typical catalysts, and reviews the progress in the understanding of reaction mechanisms. Finally, suggestions for the development of high-selectivity and high-stability catalysts for the future are presented.

The polyol oxidation to dicarboxylic acid, a crucial value-accretive reaction, is still challenging due to the paradoxical relationship between efficient activation of C-H bond and rapid desorption of carboxylic acid. Herein, we break this contradiction by constructing fully exposed Pt cluster supported on hydroxyapatite (Pt /HAP) to promote two primary hydroxyl groups of polyol oxidation to dicarboxylic acid. Such fully exposed Pt cluster with an average Pt-Pt coordination number of ∼3.4 exhibits unique electronic properties between Pt single atom and nanoparticle Pt . Specifically, gradient charge distribution in fully exposed Pt cluster shows a special synergistic effect in the C-H bond activation. Moreover, the d-band centre of fully exposed Pt cluster moderately far from the Fermi level weakens the adsorption of C = O bond in dicarboxylic acid product. As a result, fully exposed Pt /HAP with better catalytic activity (turnover frequency: 619.1 h ) shows nearly 10 times and 1.5 times of tartronic acid selectivity than Pt single atom and nanoparticle Pt catalysts, respectively. The system is also applicable to other polyol oxidation to dicarboxylic acids with noteworthy catalytic results.

The surface electron density significantly affects the photocatalytic efficiency, especially the photocatalytic CO reduction reaction, which involves multi-electron participation in the conversion process. Herein, we propose a conceptually different mechanism for surface electron density modulation based on the model of Au anchored CdS. We firstly manipulate the direction of electron transfer by regulating the vacancy types of CdS. When electrons accumulate on vacancies instead of single Au atoms, the adsorption types of CO change from physical adsorption to chemical adsorption. More importantly, the surface electron density is manipulated by controlling the size of Au nanostructures. When Au nanoclusters downsize to single Au atoms, the strong hybridization of Au 5d and S 2p orbits accelerates the photo-electrons transfer onto the surface, resulting in more electrons available for CO reduction. As a result, the product generation rate of Au /Cd S manifests a remarkable at least 113-fold enhancement compared with pristine Cd S.