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The pulping properties of blue-coke are studied. The effects of different grinding time, particle size gradation, additive type and additive concentration on pulping properties are investigated. The results show that the blue-coke can be made into blue-coke slurry under certain conditions, and the calorific value and viscosity of the prepared blue-coke slurry can meet the requirements of fuel and gasification coal water slurry. The optimal preparation scheme of blue carbon slurry is as follows: when the coal grinding time is 42 s, 200 g blue-coke sample can achieve the optimal particle size gradation, and the compound 819 additive is better than the conventional naphthalene sulfonate additive. The optimal addition amount of additive compound 819 is 1.5% of blue-coke sample dry basis, and the concentration of blue-coke slurry is preferably 65%. At this time, the calorific value can reach 18 500 kJ/t and the viscosity is about 600 mPa ⋅ s. [ABSTRACT FROM AUTHOR]

The electrochemical CO2 reduction to desired chemical feedstocks is of importance, yet it is still challenging to obtain high production selectivity with low overpotential at a current density surpassing the industry benchmark of 100 mA cm−2. Herein, we constructed a low‐cost Zn single‐atom anchored on curved N‐doped carbon nanofibers (Zn SAs/N−C) by a facile noncovalent self‐assembly approach. At a low overpotential of only 330 mV, the Zn SAs/N−C exhibited simultaneously both a high current density up to 121.5 mA cm−2 and a CO FE of 94.7 %, superior to the previous reports. Experiments and DFT calculations revealed that the Zn atoms in Zn−N4 acted as the active sites, while adjacent pyridine‐N coupled with Zn−N4 could synergistically decrease the free energy barrier for intermediate *COOH formation. Importantly, the curvature of catalyst induced Zn 3d electrons that were bound to the Zn−N bonds to return to Zn atom, thereby leading to an increase in electron density of Zn and accelerating CO2 electroreduction to CO. [ABSTRACT FROM AUTHOR]

The electrochemical CO2 reduction to desired chemical feedstocks is of importance, yet it is still challenging to obtain high production selectivity with low overpotential at a current density surpassing the industry benchmark of 100 mA cm−2. Herein, we constructed a low‐cost Zn single‐atom anchored on curved N‐doped carbon nanofibers (Zn SAs/N−C) by a facile noncovalent self‐assembly approach. At a low overpotential of only 330 mV, the Zn SAs/N−C exhibited simultaneously both a high current density up to 121.5 mA cm−2 and a CO FE of 94.7 %, superior to the previous reports. Experiments and DFT calculations revealed that the Zn atoms in Zn−N4 acted as the active sites, while adjacent pyridine‐N coupled with Zn−N4 could synergistically decrease the free energy barrier for intermediate *COOH formation. Importantly, the curvature of catalyst induced Zn 3d electrons that were bound to the Zn−N bonds to return to Zn atom, thereby leading to an increase in electron density of Zn and accelerating CO2 electroreduction to CO. [ABSTRACT FROM AUTHOR]

Electrochemical reduction of CO2 to carbon monoxide (CO) and other useful fuels/chemicals offers a green and promising technical solution for alleviating greenhouse effect and creating economic benefits. Herein, we developed a single‐atom Fe dispersed on N‐doped carbons nanosheet (Fe−SA/NCS−X) for CO2 electroreduction by direct pyrolysis of hemin‐doped polyaniline fabricated by in‐situ chemical polymerization. The Fe‐SA/NCS‐700 achieved a Faraday efficiency of CO up to 87 % at −0.45 V vs. RHE, a low onset overpotential of 105 mV and remarkable durability with the current density being maintained for 10 h constant electrocatalysis, which were comparable to the latest reported single‐atom catalysts. The Tafel slope of Fe‐SA/NCS‐700 was measured to be about 67 mV/dec, close to theoretical value of 59 mV/dec, which indicated a rapid pre‐equilibrating one‐electron transfer followed by a rate‐determining reaction step. DFT calculations revealed that the graphitic N species can synergistically improve the catalytic activities of Fe‐N4 sites of Fe‐SA/NCS−X by significantly lowering the free energy barriers of *COOH intermediate formation, thus promoting CO2 electroreduction to CO. [ABSTRACT FROM AUTHOR]

The electroreduction of carbon dioxide (CO2) to value-added chemicals is a promising strategy for alleviating both the greenhouse effect and the energy crisis. However, conventional electrocatalysts generally suffer from low energy efficiency and poor product selectivity and durability. Herein, one/two-dimensional nitrogen-doped carbon nanorod arrays/ultrathin carbon nanosheet catalysts (1D/2D NR/CS-X) with high specific surface area and N doping were designed and prepared by in situ polymerization of aniline in the presence of ultrathin carbon nanosheets originating from the thermal expansion of calcium gluconate and acid treatment, followed by pyrolysis. 1D/2D NR/CS-900 was capable of converting CO2 to CO with the Faraday efficiency of up to 94.2% at −0.45 V vs. RHE, retaining its activity for at least 30 h, and exhibited an onset overpotential as low as 97 mV, which surpassed all the reported doped carbon materials and was comparable to single-atom metal catalysts. The Tafel slope of 1D/2D NR/CS-900 was only 65 mV dec−1, which indicated a rapid pre-equilibrating one-electron transfer followed by a rate-determining reaction step. DFT calculations revealed that the pyridinic N and unique 1D/2D structure of NR/CS-X could significantly lower the free energy barriers of *COOH and *CO intermediate formation and boost CO desorption; this led to the highly efficient electroreduction of CO2 to CO. [ABSTRACT FROM AUTHOR]

In this work, a metastable aqueous interface was fabricated for synthesizing mesoporous and high surface area MnO 2 . When urea was used as the additive, hierarchical spheres self-organized from ultrathin nano-sheets were obtained. Its porous structure could be controlled through adjusting the urea concentration, and a maximum surface area of 407 m 2 g −1 was achieved by this method, which is larger than the reported values. Due to the porous structure and high surface area, as-prepared MnO 2 exhibited a specific capacitance of 775.4 F g −1 at a current density of 0.1 A g −1 , and exhibited a 63.5% capacitance retention when the current density was increased from 0.1 A g −1 to 5 A g −1 . Durability studies showed a 63.7% capacitance retention after 2500 cycles. The metastable interfacial reaction approach could also be extended to other alloys with large surface area and porous structure, such as CoB alloy. This method provides a simple and low-cost method to synthesize high surface area and mesoporous materials. [ABSTRACT FROM AUTHOR]

Electrochemical reduction of CO2 to carbon monoxide (CO) and other useful fuels/chemicals offers a green and promising technical solution for alleviating greenhouse effect and creating economic benefits. Herein, we developed a single‐atom Fe dispersed on N‐doped carbons nanosheet (Fe−SA/NCS−X) for CO2 electroreduction by direct pyrolysis of hemin‐doped polyaniline fabricated by in‐situ chemical polymerization. The Fe‐SA/NCS‐700 achieved a Faraday efficiency of CO up to 87 % at −0.45 V vs. RHE, a low onset overpotential of 105 mV and remarkable durability with the current density being maintained for 10 h constant electrocatalysis, which were comparable to the latest reported single‐atom catalysts. The Tafel slope of Fe‐SA/NCS‐700 was measured to be about 67 mV/dec, close to theoretical value of 59 mV/dec, which indicated a rapid pre‐equilibrating one‐electron transfer followed by a rate‐determining reaction step. DFT calculations revealed that the graphitic N species can synergistically improve the catalytic activities of Fe‐N4 sites of Fe‐SA/NCS−X by significantly lowering the free energy barriers of *COOH intermediate formation, thus promoting CO2 electroreduction to CO. [ABSTRACT FROM AUTHOR]

Formate, as an important chemical raw material, is considered to be one of the most promising products for industrialization among CO 2 electroreduction reaction (CO 2 RR) products, but it still suffers from poor selectivity and a low formation rate at a high current density on account of the competitory hydrogen evolution reaction. Herein, the heterogeneous nanostructure was constructed by anchoring In 2 O 3 nanoparticles on poly(3,4-ethylenedioxythiophene) (PEDOT)-modified carbon black (In 2 O 3 /PC), in which the PEDOT polymer interface layer could immobilize In 2 O 3 nanoparticles and obtain a notable reduction in electron transfer resistance among the In 2 O 3 particles, showing a 27% increase in the total electron transfer rate. The optimized In 2 O 3 /PC with rich heterogeneous interfaces selectively reduced CO 2 to formate with a high FE of 95.4% and a current density of 251.4 mA cm -2 under -1.18 V vs RHE. Also, the formate production rate for In 2 O 3 /PC was up to 7025.1 μmol h -1 cm -2 , surpassing most previously reported CO 2 RR catalysts. The in situ XRD results revealed that In 2 O 3 particles were reduced to metallic indium (In) as catalytic active sites during CO 2 RR. DFT calculations verified that a strong interface interaction between In sites and PC induced electron transfer from In sites to PC, which could optimize the charge distribution of active sites, accelerate electron transfer, and elevate the p-band center of In sites toward the Fermi level, thereby lowering the adsorption energy of *OCHO intermediates for CO 2 conversion to formate.

It is of great significance to construct heterojunctions using industrially produced co-catalysts. The direct Z-scheme composite photocatalyst provides an effective separation of photogenerated carriers. Herein, a kind of novel 2D/3D direct Z-scheme NiFe-LDH/Zn 0.5 Cd 0.5 S is prepared. Compared with fresh catalysts, the NiFe-layered double hydroxide (LDH)/Zn 0.5 Cd 0.5 S composite exhibits advantages including excellent visible light response ability and photoelectric performance and improved H 2 evolution rate by 11.6 times. Combining with theoretical calculations, ESR, XPS, and experimental results, the direct Z-scheme mechanism of the photocatalytic reaction is proposed. There is a channel for electron transfer between Zn 0.5 Cd 0.5 S and NiFe-LDH, and the electrons of Zn 0.5 Cd 0.5 S directly combine with the valence band holes of NiFe-LDH. Finally, the electrons remaining on NiFe-LDH can reduce H + to generate H 2 . This process effectively achieves separation of photogenerated carriers and increases photocatalytic H 2 evolution.