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Coal strongly adsorbs methane and during the adsorption process there is always a thermal effect that leads to some changes in the coal structure and temperature. These changes have an electrical effect, such as a change in coal resistivity. The investigation of the thermoelectric effect of the adsorption process of coal has long been a hot research issue to industry experts and scholars. It is important that this thermoelectric effect be well understand with respect to the energy transfer and translation in the adsorption process, as well as to support geophysical electrical prospecting and disaster prediction. Both domestic and international scholars have conducted many studies on this issue. The heating and electrical effects in the process of coal adsorption are interrelated. Previous research has primarily addressed the single characteristic of gas adsorption or its application, with little attention being paid to their correlation. Most studies have used adsorption quantity to reflect the coal adsorption ability, and few have focused on the thermoelectric effect to study coal adsorption. Studies regarding coal particle size and the thermoelectric effect are even rarer. In this study, we investigated the temperature change and the current vs. time curves of three different metamorphic grade briquette coals, which consist of five different coal particle sizes, at a temperature of 25℃ and pressure of 3 MPa in the coal gas adsorption process. To do so, we used a SH-X multi-channel temperature tester and CHI660E electrochemical workstation. To determine the adsorption ability of coal with respect to the thermoelectric effect, we used the Clausius-Lapeyron equation to analyze the thermoelectric effect mechanism of coal and its correlation in the coal gas adsorption process of different particle sizes. The results show that an obvious thermoelectric effect accompanies the coal gas adsorption process. The temperature of the coal increases from 0.93℃ to 8.74℃ and the resistivity of the coal decreases 0.14-0.16 times from that of its stability when it reaches adsorption equilibrium. We found the temperature of the coal to increase as the particle size decreased and the gas adsorption quantity increased, but the coal resistivity change was the opposite. Coal temperature and resistivity change are strongly correlated with the gas adsorption quantity, with the correlation coefficients rd and rw ranging between 0.9502-0.9899 and -0.9316 to -0.9916, respectively, which are close to±1. Therefore, the heat adsorption process can reflect the adsorption ability of coal. When reaching equilibrium, the greater the temperature change, the higher the temperature and the lower the resistivity, which means that the adsorption capacity is greater, and in contrast, the adsorption capacity is weaker.

This study tested the current vs. voltage curves of coals with angles of 0°, 30°, 45°, 60°, and 90° between the bedding plane and the axial direction at temperatures from 0 to 95℃ using a CHI660E electrochemical workstation. The concept of the series-parallel dominant degree was put forward. Moreover, the influence mechanism and the rule of the bedding structure of anthracite coal on coal resistivity under different temperatures were analyzed and investigated using the principle of minimum potential energy and polarization charge. The results show that the resistivity of the anthracite coal exhibits a strong regularity with temperature rise. A turning point appears at 55℃ for θ of the 0° samples, whereas the other samples have a turning point at 35℃. The series-parallel dominant degree reflects the impact mechanism of the bedding structure on coal resistivity and depends on the number of key bedding surface and the start time of the current going through. The resistivity increases with the increasing θ. In addition, the anisotropy coefficient of the anthracite coal increases with the temperature rise and elevates nearly twice in the scope of 35 to 65℃.

Using the Fluent dynamic mesh model to realize the 4D dynamic movement of a gob and inputting the kinetic mechanism of coal low-temperature oxidation and the dynamic change of heterogeneous porosity into Fluent through the user defined function,4D dynamic simulation is performed on the spontaneous heating law in a gob for U + L ventilation of a certain mine. The results show that unsteady heterogeneous porous media can be more realistic in response to the change of porosity,which exponentially decreases with time. The greater the advancing speed of the working face, the smaller the heating rate, and the average heating rate at an advancing speed of 3.6 m·d-1 is 1/5 of that at an advancing speed of 1.2 m·d-1. However, the higher the advancing speed, the deeper the depth of the high temperature region, which is unfavorable for the prevention from spontaneous combustion of coal. Because of the existence of a tail roadway in the gob, the temperature field expands, the temperature rises, the main way to release CO is the tail roadway, and the amount of CO from the tail roadway is 10 times that from the outlet. Finally, the results are verified by the field test data, indicating that the simulation results are correct and reliable.

Under the ventilation condition of U + L, a crossheading has important impact on spontaneous combustion of residual coal in a gob area. In order to ensure mine safety and obtain parameters to prevent spontaneous combustion of residual coal, on the basis of the mechanism of coal oxidation and using UDF to incorporate the reaction mechanism into FLUENT, multi-field coupling numerical simulation was performed to study the distribution law of the oxidization and heat accumulation zone in a gob with a cross-heading. The results show that the air flow field, oxygen concentration field and temperature field all change when the crossheading exists, the oxidization and heat aeeumulation zone not only offsets to the return-side but also becomes deeper and wider. The distance between the erossheading and working surface affects the width of the oxidization and heat accumulation zone, and when it is 20 m, the maximum width is approximately 25 m. After 10 d of reaetion, the heating rate at the high temperature point can reach 1.24K·d-1 in the U + L ventilation system, which is 1.5 times that in the U ventilation system. However, the position of the crossheading has little effect on the high temperature point. The temperature nearby the crossheading is the highest in the return-side temperature field of the U + L ventilation system, and the average temperature is d K higher than the same location temperature in the U system per day. With increasing distance from the crossheading to working face, the heating rate in the crossheading rim increases from 0.1 K·d-1 to 0.9 K·d-1. Although the crossheading does not belong to the high temperature region in the whole temperature field, it has good warming potential.

Hole transport layer‐free, carbon‐based, all‐inorganic CsPbI3 perovskite solar cells (PSCs) have exhibited great potential in photovoltaic applications owing to their low cost and excellent thermal stability. However, the low power conversion efficiency (PCE) hampers its development, mainly due to the existence of defects inside the CsPbI3 film or at TiO2 electron transport layer/CsPbI3 interface. Herein, these issues were addressed through a facile TiO2 post‐treatment strategy using 1‐butyl‐3‐methylimidazole hexafluorophosphate (BMIMPF6) ionic liquid. First, BMIMPF6 can passivate TiO2/CsPbI3 interface defects by forming strong bond between the electron‐rich N atoms and uncoordinated ions. Second, BMIMPF6‐modified TiO2 shows reduced hydrophilicity, inducing decreased heterogeneous nucleation and is favorable for obtaining high‐quality CsPbI3 film. Thirdly, the non‐volatile BMIMPF6 can diffuse to the perovskite film surface during annealing, further passivating defects located at perovskite grain boundaries and surface. Based on this one‐step ionic liquid interface‐to‐bulk modification, the modified device achieves a champion PCE of 15.09%, which is 14% higher than the control device (13.27%). In addition, the modified device also shows enhanced long‐term stability, which remains 96% of initial PCE after 30 days storage in dry air. The work demonstrates the superiority of multifunctional ionic liquid applied to all‐inorganic carbon‐based PSCs, providing a guidance for its commercialization. [ABSTRACT FROM AUTHOR]

In a gob with U + L ventilation, a tail roadway exists, which has important effects on the oxidation heating process and gas concentration in gob areas. Research on the heating process and gas concentration in the “U+L” ventilation can provide the basis for the prevention of spontaneous combustion, thus, the regularities of the oxidation heating process and gas concentration in gob areas were researched by simulation. Results showed that compared with U ventilation, U + L ventilation caused the high temperature zone and high temperature points in the gob areas to increase in depth and width and to be influenced by the distance between the crossheading of the tail roadway and workface. The heating rate of the high-temperature point in the gob with tail roadway was 1.5 times of that in gob without tail roadway, but was unaffected by the location of the tail roadway. Tail roadway had diversion effects on the airflow, especially near return side and the maximum reduction of gas concentration can be 0.36%.

The performance of the self-powered photodetectors based on the Cu2O/electrolyte heterojunctions is optimized by adjusting morphology and structure of the Cu2O film. The Cu2O film with a deposition time of 2000 s possesses a largest current density of 559.6 μA/cm2 under visible light illumination at zero bias, with a rising time of 5.2 ms and a recovering time of 9.0 ms. This optimized Cu2O film has a highest responsivity of about 25.8 mA/W for visible light, and a negligible responsivity for UV light. The high crystallinity and excellent charge transfer property are responsible for the improved photodetection performance. [ABSTRACT FROM AUTHOR]

The interaction between catalyst and support plays an important role in electrocatalytic hydrogen evolution (HER), which may explain the improvement in performance by phase transition or structural remodeling. However, the intrinsic behavior of these catalysts (dynamic evolution of the interface under bias, structural/morphological transformation, stability) has not been clearly monitored, while the operando technology does well in capturing the dynamic changes in the reaction process in real time to determine the actual active site. In this paper, nitrogen-doped molybdenum atom-clusters on Ti 3 C 2 T X (Mo ACs /N-Ti 3 C 2 T X ) is used as a model catalyst to reveal the dynamic evolution of Mo Acs on Ti 3 C 2 T X during the HER process. Operando X-ray absorption structure (XAS) theoretical calculation and in situ Raman spectroscopy showed that the Mo cluster structure evolves to a 6-coordinated monatomic Mo structure under working conditions, exposing more active sites and thus improving the catalytic performance. It shows excellent HER performance comparable to that of commercial Pt/C, including an overpotential of 60 mV at 10 mA cm -2 , a small Tafel slope (56 mV dec -1 ), and high activity and durability. This study provides a unique perspective for investigating the evolution of species, interfacial migration mechanisms, and sources of activity-enhancing compounds in the process of electroreduction., (© 2023 Wiley-VCH GmbH.)