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By performing DFT computations, we proposed a promising strategy to tune the ORR/OER catalytic performance of transition metal-nitrogen-carbon by constructing heterostructure with graphdiyne. We found the d-band center and charge transfer of the TM active sites can correlate the ORR/OER catalytic activity and their electronic properties for TM N C/GDY. [Display omitted] • The catalytic activities of the heterostructure between TM N C with GDY (TM N C/GDY) for ORR/OER were studied by means of density functional theory. • Co N C/GDY can be proposed as a bifunctional catalyst for ORR/OER with low overpotential. • According to the constant-potential method, the acidic condition is conducive to boost bifunctional catalytic activity for Co N C/GDY. Exploring high-efficiency electrocatalysts to boost the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is pivotal to the large-scale applications for clean and renewable energy technologies, such as fuel cells, water splitting, and metal–air batteries. Herein, by means of density functional theory (DFT) computations, we proposed a strategy to modulate the catalytic activity of transition metal-nitrogen-carbon catalysts through their interface engineering with graphdiyne (TM N C/GDY). Our results revealed that these hybrid structures exhibit good stability and excellent electrical conductivity. Especially, Co N C/GDY was identified as a promising bifunctional catalyst for ORR/OER with rather low overpotentials in acidic conditions according to the constant-potential energy analysis. Moreover, the volcano plots were established to describe the activity trend of the ORR/OER on TM N C/GDY using the adsorption strength of the oxygenated intermediates. Remarkably, the d-band center and charge transfer of the TM active sites can be utilized to correlate the ORR/OER catalytic activity and their electronic properties. Our findings not only suggested an ideal bifunctional oxygen electrocatalyst, but also provided a useful strategy to obtain highly efficient catalysts by interface engineering of two-dimensional heterostructures. [ABSTRACT FROM AUTHOR]

This article investigated the interaction mechanism between carbon monoxide (CO) and lignite organic matter in lignite liquefaction systems. The study found that a CO atmosphere can facilitate lignite conversion, but its hydrogen supply capacity is poor, resulting in lower liquefaction effects compared to an H 2 atmosphere. Increasing the initial reaction pressure and CO content can enhance the conversion of lignite to low molecular compounds. In-situ studies on lignite pyrolysis in CO and N 2 atmospheres show that CO plays an effective role in promoting the fracture of multiple hydrogen bonds present in lignite, which is linked to the water-gas shift reaction that CO takes part. Additionally, CO can also facilitate the breaking of oxygen-containing ether bonds in lignite, thereby eliminating oxygen and producing CO 2 in the gaseous phase. Density functional theory (DFT) calculations demonstrate that CO reacts with the group after the ether bond breaks, which reduces the formation energy of the product and promotes the ether bond breaking. In summary, CO in syngas may benefit the breaking of ether and hydrogen bonds in lignite during liquefaction, thus promoting lignite conversion. [Display omitted] • The interaction mechanism between CO and lignite organic matter in liquefaction was studied. • CO in syngas may be beneficial to the breaking of ether bond and hydrogen bond in lignite. • CO can promote the conversion of lignite to low molecular compounds during liquefaction. [ABSTRACT FROM AUTHOR]