Study on the characteristics of gas permeability of coal under loaded stress

The #3 coal seam of Jinsheng Rundong Ltd. of Jin-Coal Group in Shanxi Province, China, has high gas content and pressure; however, it has a low gas permeability, which can easily cause gas enrichment and may cause accidents of coal and gas outbursts. In this work, the characteristics of gas seepage were thoroughly studied by designing and modifying the ‘complete stress-strain tri-axial servo temperature-controlled test system’. The study was conducted based on four factors: Axial pressure, confining pressure, effective stress and gas pressure. We found that the axial pressure has a weak impact on coal gas permeability, indicated by a linear relationship. The confining pressure, however, has a strong impact on gas permeability, showing an exponential relationship. The relationship between permeability and gas pressure was identified as a second-order polynomial function. The functional relationship between gas permeability and axial pressure, confining pressure, effective stress, gas pressure was analyzed. Investigation into the natural flow rate of gas, concentration of gas drainage and damping coefficient supported the conclusion from the experimental study on the characteristics of gas seepage under loaded stress

Enhanced Electrocatalysis for Energy-Efficient Hydrogen Production over CoP Catalyst with Nonelectroactive Zn as a Promoter

As a non-toxic species, Zn fulfills a multitude of biological roles, but its promoting effect on electrocatalysis has been rarely explored. Herein, the theoretic predications and experimental investigations that non-electroactive Zn behaves as an effective promoter for CoP-catalyzed hydrogen evolution reaction (HER) in both acidic and alkaline media is reported. Density function theory calculations reveal that Zn doing leads to more thermal-neutral hydrogen adsorption free energy and thus enhanced HER activity for CoP catalyst. Electrochemical tests show that a Zn0.08Co0.92P nanowall array on titanium mesh (Zn0.08Co0.92P/TM) needs overpotentials of only 39 and 67 mV to drive a geometrical catalytic current of 10 mA cm(-2) in 0.5 m H2SO4 and 1.0 m KOH, respectively. This Zn0.08Co0.92P/TM is also superior in activity over CoP/TM for urea oxidation reaction (UOR), driving 115 mA cm(-2) at 0.6 V in 1.0 m KOH with 0.5 m urea. The high HER and UOR activity of this bifunctional electrode enables a Zn0.08Co0.92P/TM-based two-electrode electrolyzer for energy-saving hydrogen production, offering 10 mA cm(-2) at a low voltage of 1.38 V with strong long-term electrochemical stability