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[Display omitted] Engineering platinum-free catalysts for hydrogen evolution reaction (HER) with high activity and stability is essential for electrochemical hydrogen production. In this paper, we report the synthesis of cobalt-doped AlNi 3 /NiO (Co-AlNi 3 /NiO) electrode with three-dimensional nanoporous structure via chemical dealloying method. Density functional theory (DFT) calculations reveal that Co-AlNi 3 /NiO can accelerate water adsorption / dissociation and optimize adsorption–desorption energies of H* intermediates, thus improving the intrinsic HER activity. Both the introduction of Co and Al can efficiently ameliorate the electronic density around Ni sites of NiO and AlNi 3 , which can effectively reduce the energy barrier towards Volmer–Heyrovsky reaction and thus synergistically promote the hydrogen evolution. Benefiting from the large electrochemical active surface area, high electrical conductivity and electronic effect, the nanoporous Co-AlNi 3 /NiO catalyst exhibits remarkable HER activity with an overpotential of 73 mV at a current density of 10 mA cm−2 in alkaline condition, outperforming most of the reported non-precious metal catalysts. The nanoporous Co-AlNi 3 /NiO catalyst can operate continuously over 1000 h at high current densities with a robust stability. This work provides a new vision for the development of low-cost and efficient electrocatalysts for energy conversion applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • 1D MWO 4 (M = Mn, Co, Cd) nanomaterials were synthesized by electrospinning method. • CoWO 4 nanotubes exhibited superior efficiency in degrading BPA under UV–Vis–NIR light. • The wide-spectrum responses mechanism for MWO 4 (M = Mn, Co, Cd) were explained by DFT. Broadening the absorption region to near-infrared (NIR) light is critical for the photocatalysis due to the larger proportion and stronger penetration of NIR light in solar energy. In the present paper, one-dimensional (1D) MWO 4 (M = Mn, Co, and Cd) materials synthesized by electrospinning technique, were studied by combining the density functional theory (DFT) with experiment results, which possessed the enhanced light absorption capability within the range of 200–2000 nm. It was proved that in the ultraviolet–visible (UV–Vis) region, the absorption bands of CoWO 4 and MnWO 4 samples were attributed to the metal-to-metal charge transfer mechanism, while the absorption of CdWO 4 sample may be referable to the ligand-to-metal charge transfer mechanism. In the near-infrared (NIR) region, the absorption of CoWO 4 and MnWO 4 primarily originated from the d-d orbital transitions of Mn2+ and Co2+. The photocatalytic experimental results showed that the degradation rates for bisphenol A (BPA) over CoWO 4 , MnWO 4 , and CdWO 4 photocatalysts under UV–Vis/NIR light irradiation for 140 min/12 h were 78.8 %/75.9 %, 23.8 %/21.3 %, 12.8 %/8.7 %, respectively. This research offers the novel insights into the precise construction of tungstate catalytic systems and contributes to the advancement of UV–Vis–NIR full spectrum photocatalytic technology, and lays a foundation for a cleaner and more environmental-friendly future. [ABSTRACT FROM AUTHOR]

[Display omitted] • Co 2 N C with diatomic pair sites was successfully prepared. • Co 2 N C exhibited much faster degradation kinetic rate than Co 1 N C. • More ROS were generated by the catalysis of Co 2 N C. • DFT calculation further revealed the enhanced activity of Co 2 sites. A novel strategy for better catalytic performance in terms of precisely tuning the metal atom number of active centers is gradually getting attention. In this paper, the Co atom pair sites on N -doped porous carbon was engineered. The binuclear Co 2 site structure was identified by aberration-corrected scanning transmission electron microscopy and X-ray absorption spectroscopy. As expected, the Co 2 N C display an outstanding Fenton-like catalysis activity in tetracycline degradation with turnover frequency exceeding 0.91 min−1 that is approximately 4 times higher than the conventional CoN 4 site. The EPR tests indicated that the ROS strength stimulated by the binuclear site was much stronger than that of single site. Theoretical density functional theory calculations reveal that the optimized adsorption configuration is the O1 of peroxymonosulfate (PMS) interacting with two Co atoms, leading to stronger interaction effect and electron transfer for PMS comparing to single atom sites. [ABSTRACT FROM AUTHOR]

As a high-active metal-free electrocatalyst for NH 3 production via NO reduction reaction, honeycomb carbon nanofiber achieves an NH 3 yield of 22.35 μmol h−1 cm−2 with a high Faradaic efficiency of 88.33%. [Display omitted] Electrocatalytic NO reduction is a promising technology for ambient NO removal with simultaneous production of highly value-added NH 3. Herein, we report that honeycomb carbon nanofiber coated on carbon paper acts as an efficient metal-free catalyst for ambient electroreduction of NO to NH 3. In 0.2 M Na 2 SO 4 solution, such catalyst achieves an NH 3 yield of 22.35 μmol h−1 cm−2 with a high Faradaic efficiency of up to 88.33%. Impressively, it also shows excellent stability for 10-h continuous electrolysis. Theoretical calculations reveal that the most active center of functional groups is –OH group for NO reduction with a low energy barrier (ΔG of 0.29 eV) for the potential-determining step (*NO + H → *HNO). [ABSTRACT FROM AUTHOR]

[Display omitted] • The adsorption energies of CO 2 on the surface oxygen vacancies of different crystalline In 2 O 3 were calculated using DFT. • The effect of the spatial distributions of two active components on the CO 2 hydrogenation to aromatics was studied. • The acidity of catalyst under different spatial distributions was studied through NH 3 -TPD. In tandem catalysts, not only good synergy between the two active components is required, but also the precise control of the spatial distribution between the two active components of metal oxides and zeolite is crucial for the migration and conversion of reaction intermediates in the direct conversion of CO 2 to hydrocarbons. The correlation between the metal and the acidic site of zeolite has traditionally been simplified as "the closer, the better". However, it should be noted that this principle only holds true for a portion of tandem catalysts. Therefore, this paper studied the effect of different crystalline In 2 O 3 (cubic phase, hexagonal phase, and mixed cubic/hexagonal phase) and sheet HZSM-5 zeolite tandem catalysts on the activity of CO 2 hydrogenation reaction under different spatial distribution. The generalized gradient approximation (GGA) of density functional theory (DFT) were used to simulate the adsorption energy of CO 2 by oxygen vacancy on c-In 2 O 3 (1 1 1) and h-In 2 O 3 (1 0 4) planes, it was found that O v1 on c-In 2 O 3 (1 1 1) and O v4 on h-In 2 O 3 (1 0 4) had the strongest adsorption energy for CO 2. In addition, it has been observed that the proximity of the two active components (e.g., during mortar mixing) results in decreased catalytic performance. This is due to the migration of metal In, which neutralizes the acid sites of zeolites and leads to inefficient conversion of methanol reaction intermediates to aromatics. As a result, CO 2 conversion and aromatic selectivity are decreased. [ABSTRACT FROM AUTHOR]

[Display omitted] • A new MgFe 2 O 4 /Bi 2 WO 6 composite photocatalyst was successfully prepared by wet ball milling process. • Through DFT calculations and a series of characterizations, it was confirmed that the MgFe 2 O 4 /Bi 2 WO 6 composite material conforms to the Z-scheme electron transfer mechanism. • The degradation rate of TCH by 25%-MgFe 2 O 4 /Bi 2 WO 6 composite photocatalytic material is as high as 95.82%. • · OH and · O 2 – are the main active substances in this photocatalytic reaction. • The composite has high stability in repeated experiments. In this study, a new Z-scheme MgFe 2 O 4 /Bi 2 WO 6 heterojunction was successfully prepared by hydrothermal and wet ball milling process. The results of the study showed that after 90 min of visible light exposure, the photocatalytic degradation of tetracycline hydrochloride (TCH) by 25%-MgFe 2 O 4 /Bi 2 WO 6 heterojunction was as high as 95.82%, and the highest photocatalytic rate (0.0281 min−1) was 4.61 and 3.43 times higher than that of pure Bi 2 WO 6 (0.0061 min−1) and MgFe 2 O 4 (0.0082 min−1), respectively. Furthermore, spin-polarized density functional theory (DFT) calculations were performed to provide additional evidence of the presence of a Z-scheme charge transfer mechanism between MgFe 2 O 4 and Bi 2 WO 6. We investigated the effects of initial TCH concentration, pH, coexisting ions and different water sources on the efficiency of photocatalytic degradation of TCH in composite samples. The recovery experiments demonstrated that the MgFe 2 O 4 /Bi 2 WO 6 composites had good stability and repeatability. A series of experimental results showed that 25%-MgFe 2 O 4 /Bi 2 WO 6 had a larger specific surface area, better ultraviolet and visible absorbance, superior charge transfer and higher efficiency of photogenerated electron-hole pair separation. This paper provides new ideas for the design and preparation of new Z-scheme heterojunctions and has great prospects for practical applications in the field of wastewater treatment. [ABSTRACT FROM AUTHOR]

Atomically precise Ni 6 (SC 2 H 4 Ph) 12 nanoclusters (Ni 6 NCs) supported on g-C 3 N 4 nanosheets were constructed to enhance the photocatalytic hydrogen evolution performances. [Display omitted] Much effort has been devoted to improving the photocatalytic capacity of graphitic carbon nitride (g-C 3 N 4). In this paper, we reported the successful synthesis of a hybrid photocatalyst with superb photocatalytic hydrogen production activity through decorating atomically precise Ni 6 (SC 2 H 4 Ph) 12 nanoclusters on g-C 3 N 4 nanosheets (labeled as Ni 6 /g-C 3 N 4) at room temperature. Zeta potential experiments demonstrated that the electrostatic interaction between Ni 6 and g-C 3 N 4 led to the formation of Ni 6 /g-C 3 N 4. The photocatalytic measurements revealed that the 5 %-Ni 6 /g-C 3 N 4 prepared with the original mass ratio of m(Ni 6)/m(g-C 3 N 4) = 1/20 exhibited the strongest hydrogen production activity. In the system with triethanolamine (TEOA) as the sacrifice agent, the visible-light hydrogen production rate reached up to 5.87 mmol h−1 g−1, approximately 290 times higher than that of pure g-C 3 N 4 (0.02 mmol h−1 g−1). Density functional theory (DFT) calculations testified that the above significant enhancement of photocatalytic hydrogen evolution of the hybrid photocatalyst arose from the photogenerated electrons transfer from Ni 6 to g-C 3 N 4. [ABSTRACT FROM AUTHOR]

Multiple active-sites of Fe-N 4 , pyridinic N C and pore defect co-exist in the as-prepared single-atom Fe N C catalyst, which synergistically promote a high-efficiency oxygen reduction electrocatalysis by a combination of experimental results and DFT calculations. [Display omitted] • High N -content melamine foam as the self-sacrificed template can produce pyridinic N C active-site. • Spatial location confinement through π-π interaction between phthalocyanine-based macrocycles can make for dense Fe-N 4 active-site. • Zn-evaporation can create pore defect active-site which will meanwhile anchor pyridinic N C and Fe-N 4 active-sites. • The experimental results and DFT calculations suggest that multiple active-sites of Fe-N 4 , pyridinic N C and pore defect can synergistically promote a high-efficiency ORR electrocatalysis. Revealing the types of and interplays among multiple active-sites in iron-nitrogen-carbon (Fe N C) materials is of great significance for developing high-performance, Fe-based non-precious metal catalysts for oxygen reduction reaction (ORR). In this paper, a single-atom Fe N C catalyst is prepared through high-temperature pyrolyzing of melamine foam (MF), iron phthalocyanine (FePc), phthalocyanine (Pc), and zinc (Zn)-salts composite. The catalyst is found to contain a variety of active-sites, including carbon atom next to pyridinic-N (pyridinic N C), Fe-N 4 and pore defect. It is shown that MF with high N -content is responsible for the formation of the main pyridinic N C sites and in the meantime acts as the self-sacrificed template for framework of the catalyst. The presence of Pc can facilitate the formation of the predominant Fe-N 4 sites, since the interplay between Pc and FePc results in a confinement of Fe-N 4. Zn-salts serve as the pore-forming additives to create sufficient pore defects which can also anchor pyridinic N C and Fe-N 4 structures. The results of density functional theory (DFT) calculations suggest that the multiple active-sites function synergistically to enable high-efficiency ORR electrocatalysis. The optimal Fe N C catalyst shows superior ORR activity with a half-wave potential of ∼0.88 V (vs. RHE), as well as high methanol tolerance and electrochemical stability compared to the commercial carbon-supported platinum (Pt/C) catalyst. [ABSTRACT FROM AUTHOR]

A carbon superstructure material (PTA-700) was synthesized by a simple self-assembly method and one-step carbonization, and showed remarkable high energy and long cycle life stability in lithium/sodium ion half battery. [Display omitted] Due to abundant resources and low prices, biomass-derived carbons as anodes for lithium ion batteries (LIBs) and sodium ion batteries (SIBs) have been widely reported. However, it is still a challenge to design a biomass-derived carbon material that has immunity to environmental influences, stable chemical composition and controllable morphology. In this paper, tannic acid (TA) as a precursor is first reported to synthesize rod structures with abundant mesopores and defects (PTA-700). These features can provide more active sites and space for lithium and sodium ions storage, which is conducive to lithium and sodium ions transfer. Excellent electrochemical performance is observed in LIBs (535 mAh/g after 100 cycles at 0.1 A/g) and SIBs (114.0 mAh/g after 3000 cycles at 1 A/g). Kinetics analysis and density functional theory (DFT) calculations were carried out to further analyze the superior lithium and sodium ions storage performance of PTA-700. More importantly, PTA-700 solves many problems faced by traditional biomass-derived carbons in commercialization. Our work suggests an effective way to develop high-performance biomass-derived carbon anode materials for LIBs and SIBs. [ABSTRACT FROM AUTHOR]

[Display omitted] • The porous few-layer bimetallic co-doped g-C 3 N 4 is prepared via a facile bottom-up method. • The bimetallic synergetic regulating effect on the electronic structure can be produced in Co/Ni-g-C 3 N 4. • The superior performance results from the improved charge separation efficiency and visible light harvestability. • This work provides meritorious guidance for new bimetallic co-doped g-C 3 N 4 photocatalysts. The low specific surface area and low charge transfer efficiency of conventional graphite carbon nitride (g-C 3 N 4) are the main obstacles to its application in photocatalytic CO 2 reduction. In this paper, graphite carbon nitride was protonated by phosphoric acid (H 3 PO 4), and a new few-layer porous carbon nitride was prepared by intercalation polymerization with doping bimetal in the cavity of g-C 3 N 4. Under visible light irradiation, the CO formation rate of Co/Ni co-doped g-C 3 N 4 can reach 13.55 μmol g−1 h−1, which was 3.9 times higher than that of g-C 3 N 4 (3.49 μmol g−1 h−1). The density functional theory (DFT) calculations showed that the addition of Co and Ni in the cavity of g-C 3 N 4 can induce bimetallic synergistic regulation of the electronic structure, thus improving the separation efficiency of charges and visible light capture ability of g-C 3 N 4. Our work has great reference value for designing and synthesizing novel bimetallic co-doped g-C 3 N 4 photocatalytic materials. [ABSTRACT FROM AUTHOR]

The bimetallic phosphide nano-interfaces are constructed only by electrochemical high-voltage activation, so as to increase the electrode capacity of about 150 % (compared to the original NiCoP electrode). The 3D cathode has an ultra-high capacity of 544.9 mAh g−1 and excellent rate performance (still about 69.5 % at 30 A g−1). The assembled NCPOH//Zn battery has excellent reversibility and long life (maintained 97 % of initial capacity after 2000 cycles) and achieves a remarkable energy density of 933.5 Wh kg−1. [Display omitted] Aqueous zinc ion batteries (AZIBs) have broad prospects in many fields because of their high theoretical capacity, high hydrogen overpotential, low equilibrium potential, low cost and high safety. However, the surface chemical reactivity of cathode is usually limited by the utilization of active materials, resulting in insensitive edge position and unsatisfactory capacity. In this paper, a simple and convenient strategy is reported, in which the bimetallic phosphide nano-interfaces are constructed only by electrochemical high-voltage activation, so as to increase the electrode capacity of about 150 % (compared to the original NiCoP electrode). Under the combined action of water and oxygen, a coating of NiCo-OH nanosheet is formed on the NiCoP nano-wall, and the surfaces are rich in low-priced mixed state with remarkable reactivity and structural stability, which is theoretically confirmed by density functional theory (DFT). As a result, the 3D cathode has an ultra-high capacity of 544.9 mAh g−1 and excellent rate performance (still about 69.5 % at 30 A g−1). The assembled NCPOH//Zn battery has excellent reversibility and long life (maintained 97 % of initial capacity after 2000 cycles) and achieves a remarkable energy density of 933.5 Wh kg−1. Our work explores the relationship between interface corrosion mechanism and corrosion surface activity, which is a powerful strategy to build metal phosphides with high surface electrochemical activity as advanced energy storage devices. [ABSTRACT FROM AUTHOR]

Mechanism of H 2 O 2 production over P-doped carbon nitride was firstly revealed based on the melon crystal structure of carbon nitride. [Display omitted] Melon-based carbon nitride (CN) is a semiconductor photocatalyst with a conduction band position suitable for photocatalytic H 2 O 2 production. However, the thermodynamic inability to adsorb O 2 molecules greatly limits its photocatalytic efficiency for H 2 O 2 production. In this paper, P-doped CN with good performance for H 2 O 2 production was synthesized by a simple one-step calcination method. The experimental results show that when the doping amount of P is about 9.0 wt% of CN, the yield of H 2 O 2 can reach 12990 μM/h/g, which is about 6.6 times as that of pure CN. The mechanism of H 2 O 2 production over P-CN was firstly revealed by using the density functional theory calculations based on the melon crystal structure of carbon nitride. The results show that P-doping is easier to the strong thermodynamic adsorption of O 2 on CN, which is more beneficial to the formation of intermediate products. Further experimental results show that the substitution of C in CN by P-doping suppresses the electron and hole recombination, and therefore promoting the photocatalytic performance of P-doped CN. [ABSTRACT FROM AUTHOR]

Sovolthermally synthesized Co-MOFs exhibits high activity and stability for water oxidation. [Display omitted] The development of efficient and robust non-precious electrocatalysts for water oxidation at a mild condition is extremely desirable for industrial water splitting. Herein we developed a facile solvothermal strategy to synthesize cobalt metal organic frameworks (Co-MOFs) with sheet-like structure, which showed highly promising performance for electrocatalytic oxygen evolution. The best Co-MOF sample afforded an ultra-high oxygen evolution current density of 63.4 mA cm−2 at 1.75 V in 1 M KOH with a catalyst loading of only 0.21 mg cm−2. Notably, its electrochemical performance remained unchanged after 10,000 cyclic voltammograms indicating very promising long-term stability. Detailed study of the mechanism of the oxygen evolution by density functional theory (DFT) indicated that the strong π-conjugation formed between the central cobalt ion and adjacent aromatic rings favored the high electrocatalytic performance. The solvothermally synthesized MOFs proposed in this paper are expected to inspire the rational design of high-performance electrocatalysts for water oxidation with atomic and molecular level structural control and the exploration of structure-performance relationships to understand the electrocatalytic origin. [ABSTRACT FROM AUTHOR]

Carbon dots (CDots) with a strong greenish-yellow fluorescence in both dispersed and aggregated states are prepared. The as-prepared CDots with a size of 3.5 nm possess excellent biocompatibility, good photostability, strong solid-state luminescence, and remarkable resistance to organic solvent, allowing their applications in biological imaging in vitro and in vivo and as the color conversion layer for white light-emitting diodes. [Display omitted] Carbon dots (CDots), a class of environmentally friendly carbon-based luminescent nanomaterial, have been applied in a wide variety of fields, including bioimaging and light-emitting diodes (LEDs). Prior to these applications, however, CDots usually require modifications because some of its limitations (e.g. , the aggregation-induced luminescence quenching) make it difficult to apply in solid state. In order to realize CDots-based multiple applications simultaneously, this paper examines how CDots with a strong greenish-yellow fluorescence in both dispersed and aggregated states are prepared by microwave-assisted heating salicylic acid and thiourea. Based on control testing and the analysis of density functional theory calculations, S element from thiourea is doped into CDots and proves to be critical in governing the photoluminescence (PL) emission color. Featured with excellent biocompatibility and photostability, the dispersed CDots with photoluminescence quantum yields (32%) are able to function as a biological imaging reagent in vitro and in vivo without any side effect. Furthermore, the aggregated CDots also exhibit high photoluminescence quantum yields (26%) and remarkable resistance to organic solvent. These advantages will ensure that S-doped CDots can be applied as a color conversion layer so that white LEDs with different Commission International de L'Eclariage coordinates and tunable color temperature can be fabricated. [ABSTRACT FROM AUTHOR]

Lead(II)–benzohydroxamic acid (Pb–BHA) complex collectors perform well with respect to scheelite flotation, and, due to their structure, they are widely used for industrial purposes. This paper examines the controversial issue of whether "O, O" five-membered ring or "N, O" four-membered ring complexes are formed when BHA coordinates with Pb ions, with their structure being comprehensively studied from the aspect of colloid and interface science. The configurations of Pb–BHA complexes are examined in a solution and on a mineral surface with experimental and computational methods. Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and density functional theory (DFT) revealed that the five-membered ring is the dominant form of Pb–BHA complexes in a solution, whereas four-membered ring complexes are the stronger electron acceptor of the two. Moreover, XPS and time-of-flight secondary ion mass spectrometry (TOF-SIMS) confirmed that the four-membered ring complexes are stable with respect to being adsorbed on the scheelite surface. Therefore, although the four-membered ring is not as stable as the five-membered ring in a solution, it offers advantages with respect to adsorption on an electron-rich mineral surface during short-flotation processes. [ABSTRACT FROM AUTHOR]

The energy level diagram for electronic transfer vs. Vacuum level; (B and C) The photocatalytic mechanism over EY-sensitized UiO-66/WP. The abundant transition metal phosphides co-catalysts on the earth can satisfy the sustainable and clean solar H 2 production through photocatalytic water splitting, which is promising to replace the rare precious metals, such as Pt, Au, Pd, Ru and so on. In this paper, we use the temperature-programmed solid phase method to prepare WP nanoparticles. Based on the Density Functional Theory (DFT) calculations, we demonstrate that the WP nanoparticles possess outstanding electrical conductivity and excellent capability to transport electrons. WP nanoparticles are loaded onto the surface of UiO-66 via the ultrasound-assisted impregnation method to induce a highly efficient visible-light photocatalytic H 2 production activity of 384 µmol in 5 h, which is 10.67 times than that of pure UiO-66. The catalytic performance is attributed to the excellent metallic conductivity and the favourable Fermi level position of WP nanoparticles. Further studies of PL, TRPL and Mott-Schottky curves, we can not only know that the modification of WP nanoparticles do improve the electron transfer ability, but also that the matched work functions between the EY and UiO-66 provides a feasible thermodynamic path for the transmission of electrons. Our work demonstrates that the earth-abundant transition metal phosphides material have the potential to construct cheaper and high catalytic performance photocatalysts. [ABSTRACT FROM AUTHOR]

In this paper, the carbon-doped boron nitride nanoplate (C-BNNP) was prepared by pyrolyzing the precursor under N 2 and served as an excellent adsorbent for removal of Rhodamine B (RhB). The structure and composition of C-BNNP were characterized and its adsorption behavior for RhB was investigated. Compared with boron nitride nanoplate (BNNP) which was synthesized under NH 3 , C-BNNP displayed an enhancement of the adsorption capacity for RhB (833 mg/g). The adsorption activity was comprehensibly studied by kinetics, isotherm and thermodynamics. The adsorption kinetics followed pseudo-second-order model. The equilibrium adsorption data agreed well with the Langmuir isotherm. And the thermodynamics indicated that the adsorption process was a spontaneous, exothermic and physisorption process. In addition, the density functional theory was proposed that doping carbon in the BNNP decreased the chemical hardness of the adsorbent and enhanced the adsorption capacity of C-BNNP for RhB. [ABSTRACT FROM AUTHOR]

In this paper, density functional theory (DFT) calculation was employed to study the adsorption of nitric oxide (NO) on the highly reactive anatase TiO2 (001) surface. For comparison, the adsorption of NO on the (101) surface was also considered. Different from the physical adsorption on the (101) surface, NO molecules are found to chemisorb on the TiO2 (001) surface. The twofold coordinate oxygen atoms (O2c) on the anatase (001) surface are the active sites. Where NO is oxidized into a nitrite species (NO2-) trapping efficiently on the surface, with one of the surface Ti5c-O2c bonds adjacent to the adsorption site broken. Our results, therefore, supply a theoretical guidance to remove NO pollutants using highly reactive anatase TiO2 (001) facets. [ABSTRACT FROM AUTHOR]

TOC: The sulfur vacancies of MoS 2 is successfully patched by a facile solution method using 4-nitrothiophenol (4NTP). The gas response of 4NTP healed MoS 2 increase by about 200 % for the N -doping effect and the enhancement of physical absorption of NO 2. Besides, this method is also efficient on TMDCs like MoSe 2 , WSe 2 and WS 2. [Display omitted] • Covalently patched the sulfur vacancies of Transition Metal Dichalcogenides, which decreased the density of surface defect and improved its NO 2 sensing performance. • The Fermi-level of 4-nitrothiophenol healed MoS 2 shift toward the valence band demonstrate the n -doping process, thereby increased the carriers of MoS 2. • 4-nitrothiophenol healed MoS 2 performed a higher NO 2 response (increased by 200 %) and lower limit of detection (10 ppb). Transition metal dichalcogenides (TMDCs) garner significant attention for their potential to create high-performance gas sensors. Despite their favorable properties such as tunable bandgap, high carrier mobility, and large surface-to-volume ratio, the performance of TMDCs devices is compromised by sulfur vacancies, which reduce carrier mobility. To mitigate this issue, we propose a simple and universal approach for patching sulfur vacancies, wherein thiol groups are inserted to repair sulfur vacancies. The sulfur vacancy patching (SVP) approach is applied to fabricate a MoS 2 -based gas sensor using mechanical exfoliation and all-dry transfer methods, and the resulting 4-nitrothiophenol (4NTP) repaired molybdenum disulfide (4NTP-MoS 2) is prepared via a sample solution process. Our results show that 4NTP-MoS 2 exhibits higher response (increased by 200 %) to ppb-level NO 2 with shorter response/recovery times (61/82 s) and better selectivity at 25 °C compared to pristine MoS 2. Notably, the limit of detection (LOD) toward NO 2 of 4NTP-MoS 2 is 10 ppb. Kelvin probe force microscopy (KPFM) and density functional theory (DFT) reveal that the improved gas sensing performance is mainly attributed to the 4NTP-induced n -doping effect on MoS 2 and the corresponding increment of surface absorption energy to NO 2. Additionally, our 4NTP-induced SVP approach is universal for enhancing gas sensing properties of other TMDCs, such as MoSe 2 , WS 2 , and WSe 2. [ABSTRACT FROM AUTHOR]