Electrocatalytic nitrate reduction reaction (NITRR) represents a promising approach for ammonia synthesis, but existing application has been constrained by the complex proton-coupled electron transfer and the sluggish kinetics induced by various intermediates. Herein, we synthesized a series of metalized covalent organic frameworks: NiTP-MTAPP MCOFs (M=2H, Co, Cu, and Fe), based on dual redox-active centers: thiophene-substituted Ni-bis(dithiolene) ligand-Ni[C2S2(C4H2SCHO)2]2 and metallic porphyrin. Through regulating the adsorption and desorption of species at the catalytic sites, we have identified the optimal NITRR electrocatalyst: NiTP-CoTAPP MCOF, which achieved the highest faradaic efficiency (FE) of approximately 85.6% at -0.8V (vs. RHE) in pure nitrate solution, with an impressive yield rate of 160.2mmol h-1 g-1 cat. The generation of active hydrogen at [NiS4] sites achieved dynamic equilibrium with the timely hydrogenation reaction at CoN4 sites, effectively suppressing the hydrogen evolution reaction. Moreover, the incorporation of thiophene (TP) groups and metal ions facilitates charge transfer. Density functional theory (DFT) calculations demonstrated the reduction in energy barriers at different catalytic sites. The CoN4-NiS4 system exhibited the optimal adsorption-to-desorption capability and the lowest energy barrier (0.58eV) for the rate-determining step (*NO→*HNO), which is supported by the moderate d-band center and Bader charge value.

Abstract Electrocatalytic nitrate reduction reaction (NITRR) represents a promising approach for ammonia synthesis, but existing application has been constrained by the complex proton‐coupled electron transfer and the sluggish kinetics induced by various intermediates. Herein, we synthesized a series of metalized covalent organic frameworks: NiTP‐MTAPP MCOFs (M = 2H, Co, Cu, and Fe), based on dual redox‐active centers: thiophene‐substituted Ni‐bis(dithiolene) ligand‐Ni[C 2 S 2 (C 4 H 2 SCHO) 2 ] 2 and metallic porphyrin. Through regulating the adsorption and desorption of species at the catalytic sites, we have identified the optimal NITRR electrocatalyst: NiTP‐CoTAPP MCOF, which achieved the highest faradaic efficiency (FE) of approximately 85.6% at −0.8 V (vs. RHE) in pure nitrate solution, with an impressive yield rate of 160.2 mmol h −1 g −1 cat. The generation of active hydrogen at [NiS 4 ] sites achieved dynamic equilibrium with the timely hydrogenation reaction at CoN 4 sites, effectively suppressing the hydrogen evolution reaction. Moreover, the incorporation of thiophene (TP) groups and metal ions facilitates charge transfer. Density functional theory (DFT) calculations demonstrated the reduction in energy barriers at different catalytic sites. The CoN 4 −NiS 4 system exhibited the optimal adsorption‐to‐desorption capability and the lowest energy barrier (0.58 eV) for the rate‐determining step (*NO → *HNO), which is supported by the moderate d‐band center and Bader charge value.

Summary Hydraulic fracturing coupled with CO2 injection or CO2 prestorage fracturing is a pivotal technique for enhancing shale oil recovery. Besides, geological CO2 storage offers a feasible solution for mitigating global warming. However, after hydraulic fracturing, the shale matrix is in a water-bearing environment. The complex mechanisms associated with the impact of the injected CO2 on shale oil recovery in the water-bearing kerogen matrix remain unclear. In this work, we explored the adsorption mechanism of five representative components of shale oil in water-bearing kerogen through molecular dynamics (MD) simulation, which may provide useful microscopic insights for industrial CO2 prestorage fracturing. Our research revealed that CO2 could decrease the adsorption capacity of n-octane (OCT; saturated alkanes), thiophene (THIOP), and naphthalene rings (NAPs; aromatic hydrocarbons) onto the kerogen, which consequently improved the recovery of these components. Conversely, the adsorption capacity of pyridine (PYR) and n-octadecanoic acid (STE) was boosted upon the CO2 introduction. This could be attributed to the fact that after CO2 injection, both the quantity and the lifetime of hydrogen bonds between these two components and kerogen were increased. The interaction energy between these two components and the water-bearing kerogen also increased, which was in-line with the changes in molecular van der Waals (vdW) surface electrostatic potential (ESP) and the spatial distribution function (SDF). In addition, to reveal the deeper mechanism, the interactions between the specific sites or functional groups on the kerogen and the different components are analyzed to predict the intermolecular charge transfer. It is believed this work may offer useful insights into the design and implementation of CO2 prestorage fracturing for improved shale oil recovery and CO2 geological storage.

Carboxylic acid-based deep eutectic solvent for efficient desulfurization: Experimental and computational thermodynamics

Facile loading of CuCl on SBA-15 for adsorptive desulfurization

Connectivity isomerization of the same aromatic molecular core with different substitution positions profoundly affects electron transport pathways and single-molecule conductance. Herein, we designed and synthesized all connectivity isomers of a thiophene (TP) aromatic ring substituted by two dihydrobenzo[b]thiophene (BT) groups with ethynyl spacers (m,n-TP-BT, (m,n = 2,3; 2,4; 2,5; 3,4)), to systematically probe how connectivity contributes to single-molecule conductance. Single-molecule conductance measurements using a scanning tunneling microscopy break junction (STM-BJ) technique show ∼12-fold change in conductance values, which follow an order of 10-4.83 G0 (2,4-TP-BT) < 10-4.78 G0 (3,4-TP-BT) < 10-4.06 G0 (2,3-TP-BT) < 10-3.75 G0 (2,5-TP-BT). Electronic structure analysis and theoretical simulations show that the connectivity isomerization significantly changes electron delocalization and HOMO-LUMO energy gaps. Moreover, the connectivity-dependent molecular structures lead to different quantum interference (QI) effects in electron transport, e.g., a strong destructive QI near E = EF leads the smallest conductance value for 2,4-TP-BT. This work proves a clear relationship between the connectivity isomerization and single-molecule conductance of thiophene heterocyclic molecular junctions for the future design of molecular devices.

Diatomite supported bagel-like hydroxylated mesoporous carbon nitride towards the adsorption desulfurization application

Facile construction of hierarchically porous CPO-27-Ni by mixed ligand strategy towards enhanced adsorption desulfurization from fuels

Abstract Two new copolymers (named PTO‐BO and PTO‐HD) with alkyloxime‐substituted thiophene (TO) as acceptor unit and 6‐undecylthiopheno[3,2‐b]thiophene spacer as π‐bridge were synthesized and applied in organic solar cells (OSCs) as electron donors. PTO‐HD with 2‐hexyldecyl side chains on TO moiety possesses more suitable phase separation, more efficient exciton dissociation and charge transportation, and less charge recombination than PTO‐BO with 2‐butyloctyloxime‐substituted thiophene in OSCs with Y6 as the acceptor. As a result, the OSCs based on PTO‐HD:Y6 achieved an optimal power conversion efficiency (PCE) of 13.89% with a Voc of 0.799 V, a Jsc of 22.74 mA cm−2, and a FF of 67.67% without additives, which is higher than that (12.29%) of PTO‐BO:Y6 OSCs.

The powerful combination of 2D/2D Ni-MOF/carbon nitride for deep desulfurization of thiophene in fuel: Conversion route, DFT calculation, mechanism

In situ synthesis of mesoporous NiS2-MoS2 sphere-flower hybrid for hydrodesulfurization of thiophene and 4,6-dimethyl-dibenzothiophene

Photocatalytic oxidative demercaptanization/denitrogenation of gasoline catalyzed by MAX-phase@rGO@PW11Zn as a high-performance nanocatalyst

Conjugated porous polymers regulated by thiophene and polycyclic aromatic hydrocarbons for photocatalytic water splitting toward hydrogen production

Experimental and molecular dynamics study of fuel desulfurization process using deep eutectic solvent

Microwave-assisted rapid growth of corncob-like nano-Ag2O/ZIF-8 on PAN electrospinning nanofibers enabled highly efficient selective adsorption desulfurization

ABSTRACT Coal desulfurization is imperative to produce clean coal and reduce the emission of harmful gas during combustion. However, organic multi-ring sulfurous in coal is more difficult to remove than inorganic sulfur. Therefore, in this paper, two desulfurization methods, traditional oxidation desulfurization method nitric acid leaching (NAL) and novel reduction potassium tert-butoxide and hydrogen silane desulfurization system (KOSi), were compared to remove the organic multi-ring sulfurous in raw coal sample. The results showed that the total sulfur content reductions of NAL and KOSi were 45.21% and 31.51%, corresponding to the loss rates of calorific value were 10.32% and 5.45%, respectively. The critical factors for the higher desulfurization rate of NAL than KOSi were the decreased particle size, the generation of cracks on the coal sample and the effective removal of sulfones (SN) from thiophene (TP) oxidation. In addition, the carbon macromolecular framework of coal particles could be destroyed in NAL system, resulting in a decrease in C-C and C-H content. This was the main reason that the calorific value loss of NAL was greater than that of KOSi. The consequence of this paper would provide data support for the selection of the desulfurization method for high sulfur coal, especially consisting of multi-ring sulfurous, in terms of indicators and mechanisms.

Rational design of donor-acceptor engineered g-C3N4 for boosted H2O2 production via photocatalytic O2 reduction

Synthesis of GO/Fe–Ni MOF octahedral structure as an effective magnetic adsorbent in the removal of sulfur compounds from liquid fuel

Abstract BACKGROUNDWith strict regulations on environmental protection, the removal of sulfur compounds from fuels has become increasingly urgent by extraction desulfurization technology.RESULTSA series of ionic liquid (IL) extractants for the removal of sulfides [benzothiophene (BT), thiophene (TH) and dibenzothiophene (DBT) in model oil] was developed. The ILs with functionalized 1,8‐diazabicyclo [5.4.0] undecano‐7‐ene (DBU) cations and large volume difluoromethane sulfonimide (NTf2) anion as raw materials were synthesized. The performance of the ILs was characterized by Fourier transform infrared spectroscopy (FTIR), elemental analysis and nuclear magnetic hydrogen spectroscopy (1H‐NMR) and other methods. Maximum removal efficiencies of 65.08% TH, 83.02% BT and 89.72% DBT were achieved in the presence of [CoDBU][NTf2] with functionalized carboxylation groups. In addition extractive desulfurization (EDS) was studied by tailoring the acid–base functional groups and viscosity of ILs. FTIR and the analysis of interaction energies were adopted to explore the interaction of ILs and sulfides. This indicated that the cooperative effects of hydrogen bonding, electrostatic interaction and π‐π interaction between sulfides and ILs were closely related to the high removal efficiencies of sulfides.CONCLUSIONSThe experimental results show that [CoDBU][NTf2] with functional carboxyl group is a clean and efficient extractant suitable for removing thiophene sulfides from model fuel oil. This work provides a reference process for the desulfurization of fuel oil in industry. © 2022 Society of Chemical Industry (SCI).

Theoretical investigation on interactions between N-methylpyrrolidone-FeCl3 and components in model oil: The role of S-Fe coordination in thiophene removal