Barrier For Electron Transfer Research Articles

Enhanced electrocatalytic water splitting by manipulating d-band center of aligned MoXS (X = Co, Ni, Fe) heteronanosheet

Modulating d‑band center is an effective approach to develop efficient electrocatalyst towards robust oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). In this work, MoXS (X = Co, Ni, Fe) heteronanosheets were synthesized and vertically stacked on carbon nanosheet (MoXS/CNS). Benefiting from the modulation of d-band center through interface engineering between MoS2/XySz (X = Co, Ni, Fe), MoXS/CNS exhibited notable catalytic activities superior to MoS2/CNS towards OER and HER. Specifically, MoCoS/CNS displayed the elevated d-band center towards competitive lower electron-transfer barrier, which resulted in remarkable catalytic activity and long-term stability toward overall water splitting compared with MoNiS/CNS and MoFeS/CNS. Such strategy of manipulating d-band center by interface engineering may provide in-depth insight into transition-metal heterointerface for electrocatalytic applications.

Synthesis and electrochemical properties of sulfur-nitrogen-doped multi-walled carbon nanotubes

Multi-walled carbon nanotubes doped with sulfur and nitrogen (S-N-MWCNTs) were grown onto silicon/silicon oxide wafer by means of chemical vapor deposition upon decomposition of dimethyl sulfoxide (DMSO) and acetonitrile (ACN) in presence of catalyst. The S-N-MWCNTs were characterized by scanning electron microscopy combined with energy dispersive X-ray spectroscopy. The findings demonstrate that S-N-MWCNTs exhibit bamboo-shaped nanostructure, quite similar to pure nitrogen-doped carbon nanotubes. The S-N-MWCNTs were investigated with respect to their electrochemical response to ferrocyanide/ferricyanide, [Fe(CN)6]4-/3- in potassium chloride aqueous solutions by means of cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) techniques. The recorded CVs demonstrate strong dependence of electrochemical response, electron transfer kinetics, and sensitivity of S-N-MWCNTs on concentration of decomposed DMSO precursor. Namely, upon increasing concentration of decayed DMSO up to 2% wt. the current density, the electron transfer kinetics, and the sensitivity of S-N-MWCNTs toward [Fe(CN)6]4-/3- tend to enhance. The extracted EIS results approve that when DMSO reaches the optimum concentration of 2% wt. the barrier for electron transfer decreases significantly leading, consequently, to faster electron transfer kinetics. The S-N-MWCNTs exhibit considerable stability and excellent reproducibility, and thus it can be considered suitable analytical tool for detection of redox systems at micromolar level.

Long‐Life, High‐Rate Rechargeable Lithium Batteries Based on Soluble Bis(2‐pyrimidyl) Disulfide Cathode

AbstractOrganosulfides are promising candidates as cathode materials for the development of electric vehicles and energy storage systems due to their low‐cost and high capacity properties. However, they generally suffer from slow kinetics because of the large rearrangement of S−S bonds and structural degradation upon cycling in batteries. In this paper, we reveal that soluble bis(2‐pyrimidyl) disulfide (Pym2S2) can be a high‐rate cathode material for rechargeable lithium batteries. Benefiting from the superdelocalization of pyrimidyl group, the extra electrons prefer to be localized on the π* (pyrimidyl group) than σ* (S−S bond) molecular orbitals initially, generating the anion‐like intermedia of [Pym2S2]2− and thus decreasing the dissociation energy of the S−S bond. It makes the intrinsic energy barrier of dissociative electron transfer depleted, therefore the lithium half cell exhibits 2000 cycles at 5 C. This study provides a distinct pathway for the design of high‐rate, long‐cycle‐life organic cathode materials.

Long-Life, High-Rate Rechargeable Lithium Batteries Based on Soluble Bis(2-pyrimidyl) Disulfide Cathode.

Organosulfides are promising candidates as cathode materials for the development of electric vehicles and energy storage systems due to their low-cost and high capacity properties. However, they generally suffer from slow kinetics because of the large rearrangement of S-S bonds and structural degradation upon cycling in batteries. In this paper, we reveal that soluble bis(2-pyrimidyl) disulfide (Pym2 S2 ) can be a high-rate cathode material for rechargeable lithium batteries. Benefiting from the superdelocalization of pyrimidyl group, the extra electrons prefer to be localized on the π* (pyrimidyl group) than σ* (S-S bond) molecular orbitals initially, generating the anion-like intermedia of [Pym2 S2 ]2- and thus decreasing the dissociation energy of the S-S bond. It makes the intrinsic energy barrier of dissociative electron transfer depleted, therefore the lithium half cell exhibits 2000 cycles at 5 C. This study provides a distinct pathway for the design of high-rate, long-cycle-life organic cathode materials.

WO3/N-CDs photocatalyst with Z-scheme heterojunction for efficient tetracycline degradation under visible and near-infrared light

Using visible and near-infrared (NIR) light as excitation sources to realize the photocatalytic degradation of environmental pollutants is a promising strategy, which will broaden the application of solar energy, but some challenges still exist. Herein, a novel direct Z-scheme tungsten trioxide/nitrogen doped carbon dots (WO3/N-CDs) heterojunction photocatalyst with remarkably enhanced light-absorption and broad-response photocatalytic activity is successfully constructed. The obtained WO3/N-CDs (CDs, 5 wt%) exhibit stronger absorption properties in the NIR region than in the ultraviolet region, and superior degradation efficiency (96.0% within 1 h) towards tetracycline (TC). The reaction rate constant of 5%WO3/N-CDs reaches 0.0428 min−1, is 15.3 and 7.5 times that of N-CDs and WO3 respectively. The outstanding photocatalytic activity is on account of the intimate Z-scheme heterojunction interfacial contact, which promotes the spatial separation of electron-hole pairs, as well as reduces the barrier of electron transfer. Through morphology orientation, preferential growth of (002) crystal plane is induced, resulting in the formation of hexagonal single crystal structure of WO3, which is conducive to the construction of Z-scheme heterojunction between N-CDs and WO3. According to the analysis of energy band position and free radicals, 1O2, ·O2-, and h+ take part in the degradation process. Overall, this research might enlighten the reasonable construction of heterostructure between new carbon material and semiconductor photocatalyst to realize the utilization of broad-spectrum sunlight.

Hot-Electron-Induced Photochemical Properties of CdSe/ZnSe Core/Shell Quantum Dots under an Ambient Environment.

Using CdSe/ZnSe core-shell quantum dots (QDs) as a model, we systematically investigate the photochemical properties of QDs with the ZnSe shells under an ambient environment, which show almost opposite responses to either oxygen or water in comparison with CdSe/CdS core/shell QDs. While the ZnSe shells provide an efficient potential barrier for photoinduced electron transfer from the core to the surface-adsorbed oxygen, they also act as a stepping stone for hot-electron transfer directly from the ZnSe shells to oxygen. The latter process is so effective and competes favorably with ultrafast relaxation of hot electrons from the ZnSe shells to the core QDs, which can completely quench the photoluminescence (PL) with saturated adsorption of oxygen (1 bar) and initiate oxidation of the surface anion sites. Water can slowly eliminate the excess hole to neutralize the positively charged QDs, partially canceling the photochemical effects of oxygen. Alkylphosphines─through two distinctive reaction pathways with oxygen─stop the photochemical effects of oxygen and completely recover PL. With limited thickness (around two monolayers), the ZnS outer shells substantially slow down photochemical effects on CdSe/ZnSe/ZnS core/shell/shell QDs but cannot fully stop PL quenching by oxygen.

MOF-derived porous helical carbon nanotube/doped barium ferrite composites for enhanced microwave absorption

The magnetic-dielectric composite with a metal-organic framework (MOF) structure has been verified as an ideal candidate for effective microwave absorption. Helical multi-walled carbon nanotube (h-MWCNT)/doped barium ferrite composites were prepared using the sol-gel method. A porous MOF structure, with an abundant microscopic cavity structure and an adequate conductive network, was constructed, where the doped barium ferrite particles and h-MWCNTs overlapped through sheet-line interaction, and the uniformly dispersed barium ferrite particles were anchored inside the conductive network. The composition of h-MWCNTs has a great influence on the electromagnetic parameters and absorbing performance. After optimization, the minimum reflection loss of − 56.47 dB was achieved at 4.8 GHz, with a matching thickness of 1.35 mm. At this matching thickness, the composites reached the maximum wave-absorbing bandwidth of 6.20 GHz, covering the Ku band. The excellent microwave absorption performance could be attributed to the low energy barrier of electron transfer and the great charge transfer ability according to the experimental and calculation results. Simultaneously, a special charge transfer channel and a micro-capacitor caused by electron accumulation were generated by the interaction in the heterojunction, which consequently improved the dielectric loss capability. Further, due to abundant polarization genes and multiple magnetic resonances of the composites, the magnetic-dielectric synergetic effect also leads to an evident absorption. This novel light magnetic-dielectric MOF-derived composite shows great potential in microwave absorption applications.

Three-Channel Electron Transfer for Estimating Time Constants Correlated with Photocatalytic Photon Utilization

Although the potential barrier for semiconductor-cocatalyst interfacial electron transfer can be reduced by intensifying the irradiation, the photocatalytic reaction still suffers from a low photon utilization. We here propose a trichannel electron transfer model to demonstrate that the photogenerated oxidative intermediates deprive electrons from the photocatalyst and compete with the target reaction. This model can evaluate the time constant for each electronic process involved in the target reaction and predict photocatalytic photon utilization, which is closely related to the evolution of the oxidative intermediates.

Polaronic Mechanism of Vibronic Localization in Mixed-Valence Cation Radicals with a Non-Conjugated Chromophore on the Bridge

In quest of a controllable intramolecular electron transfer (ET) across a bridge, we study the cation-radical form of the parent 1,4-diallyl-butane (I) and its derivatives (II)-(VI). In these mixed-valence (MV) compounds, the bridge of variable length connecting allyl redox sites can be either saturated (-CH2 CH2-) (I, III, and V) or unsaturated, modified by the π-spacer (-HC═CH-) (II, IV, and VI). Ab initio calculations for the charge delocalized transition structure and for fully optimized localized form of 1,ω-diallyl cation radicals I-VI allowed us to estimate the potential barriers for ET between the terminal allyl groups, vibronic coupling, and ET parameters. The ET barrier in all compounds with the π-fragment on the bridge is shown to be higher with respect to that in the systems with a saturated bridge. We propose a model based on the concept of a specific polaronic effect of the spacer. Charge localization at an allyl group creates an electric field polarizing the π-fragment and the bridge as a whole. The induced dipole moment interacts with the localized charge giving rise to the additional vibronic stabilization in a self-consistent manner without an appreciable change of localized charge. Utilization of this spacer-driven polaronic effect is expected to provide a route to a controllable ET in bridged MV compounds.

Self-doped TiO2 nanotubes with surface modification by ionic liquids for enhanced photoreduction of CO2 to acetic acid

The photocatalytic reduction of CO2 to high-value hydrocarbons can both solve environmental problems and alleviate the energy crisis. As a room-temperature molten salt with designable anions and cations, ionic liquids are very popular in the field of CO2 capture. If combining ionic liquids with photocatalysts, simultaneous capture and conversion of CO2 are expected to be achieved. In this study, a [bmim][Tf2N] loaded self-doped TiO2 nanotubes (ILs-RTNTs) composite photocatalyst was developed for the photoreduction of CO2 to acetic acid. The acetic acid yield of ILs-RTNTs reached as high as 88.1 μmol gcat−1h−1, and there was no decrease after six cycles. Both the defects constructed by self-doping and the surface modification by ionic liquids strengthened the light utilization ability of the photocatalyst and enhanced the separation of photoinduced electron-hole pairs. Density-functional theory (DFT) calculations further revealed that the surface loading of ionic liquids introduced more active sites, strengthened the adsorption of CO2, changed the electronic structure, and lowered the energy barrier for electron transfer of the photocatalyst. This study will promote the versatile application of ionic liquids in the field of simultaneous capture and photoreduction of CO2.

Enabling Efficient Photocatalytic Hydrogen Evolution via In Situ Loading of Ni Single Atomic Sites on Red Phosphorus Quantum Dots

AbstractCurrently, red phosphorus (RP) based catalysts have shown great potential for photocatalysis due to several important intrinsic advantages. The integration of single atomic sites and RP becomes a promising solution, which has rarely been discussed. Herein, a brand‐new type of photocatalyst is proposed by in situ loading Ni single atoms on the P vacancy defects of the RP quantum dots (Ni‐RPQD), achieving the successful attempt of combining single atomic catalyst (SAC), RP, and QDs for the first time. The Ni‐P sites act as electron antennas, which attract the photocarriers to the solid‐liquid interface and activate protons to initiate an efficient hydrogen production process, resulting in a high hydrogen production rate, which is 224 times higher than that of the original RPQD and is also superior to most reported RP‐based photocatalysts and competitive with the non‐noble metal‐based SAC photocatalysts. Theoretical explorations reveal that the atomically dispersed Ni atoms significantly lower the energy barrier for electron transfer during photocatalysis. This results in enhanced adsorption and fast dissociation of water molecules for more efficient H2 generation. This study offers a significant and new direction for future developments of advanced and stable photocatalysts for water splitting.

Pushing the Limit of Open-Circuit Voltage Deficit via Modifying Buried Interface in CsPbI3 Perovskite Solar Cells.

Although CsPbI3 perovskites have shown tremendous potential in the photovoltaic field owing to their excellent thermal stability, the device performance is seriously restricted by severe photovoltage loss. The buried titanium oxide/perovskite interface plays a critical role in interfacial charge transport and perovskite crystallization, which is closely related to open-circuit voltage deficit stemming from nonradiative recombination. Herein, target molecules named 3-sulphonatopropyl acrylate potassium salts are deliberately employed with special functional groups for modifying the buried interface, giving rise to favorable functions in terms of passivating interfacial defects, optimizing energetic alignment, and facilitating perovskite crystallization. Experimental characterizations and theoretical calculations reveal that the buried interface modification inhibits the electron transfer barrier and simultaneously improves perovskite crystal quality, thereby reducing trap-assisted charge recombination and interfacial energetic loss. Consequently, the omnibearing modification regarding the buried interface endows the devices with an impressive efficiency of 20.98%, achieving a record-low VOC deficit of 0.451V. The as-proposed buried interface modification strategy renders with a universal prescription to push the limit of VOC deficit, showing a promising future in developing high-performance all-inorganic perovskite photovoltaics.

Spin-State Regulation of Nickel Cobalt Spinel toward Enhancing the Electron Transfer Process of Oxygen Redox Reactions in Lithium–Oxygen Batteries

The development of a high-energy-density lithium–oxygen (Li–O2) battery is mainly determined by highly efficient electrocatalysts with excellent activity and stability, facilitating reversible oxygen redox reactions. Engineering the electron spin state provides a novel strategy to enhance the electrocatalytic activity of electrode materials. In this work, sulfur vacancy-enriched spinel NiCo2S4 (Vs-NiCo2S4) with high spin polarization is designed as an effective electrocatalyst for high-performance Li–O2 batteries. Subtle lattice distortion is induced by sulfur vacancy in spinel Vs-NiCo2S4, which strongly contributes to the formation of high spin states of Co3+ (HS, t2g4eg2) from the low spin states of Co3+ (LS, t2g6eg0) at active octahedral sites. The electron transitions of Co3+ from low to high spin enable the increase of the spin polarization and produce abundant unpaired electrons in the 3d orbital of Co3+, enhancing the adsorption of oxygen intermediates and boosting the electron transfer process of oxygen redox reactions. Density functional theory calculations indicate that the spin magnetic moment of Co3+ in Vs-NiCo2S4 is raised in comparison to that in NiCo2S4, which improves the catalytic activity of the material via lowering the energy barrier for electron transfer. Experimentally, Vs-NiCo2S4-based Li–O2 batteries exhibit a large specific capacity of 8707.0 mAh g–1 and long cycling life of 487 h. Furthermore, in situ differential electrochemical mass spectrometry results show that the ratio of electron to oxygen during oxygen redox reactions is close to 2, demonstrating the favorable formation and decomposition of Li2O2 on Vs-NiCo2S4 in a Li–O2 battery. This work presents a powerful strategy to rationally design efficient electrocatalysts via spin engineering to boost oxygen redox reaction kinetics in Li–O2 batteries.

Heterogeneous activation of peroxymonosulfate by magnetic hybrid CuFe2O4@N-rGO for excellent sulfamethoxazole degradation: Interaction of CuFe2O4 with N-rGO and synergistic catalytic mechanism

In order to address the low catalytic performance of magnetic CuFe2O4 caused by the agglomeration, low conductivity and potential metal ion leaching risk, N-doped reduced graphene oxide (N-rGO) with high charge density and rich active sites was employed as support to synthesize CuFe2O4@N-rGO (CuFe@NG), which was used for peroxymonosulfate (PMS) activation to degrade sulfamethoxazole (SMX). Results showed that the CuFe@NG/PMS system exhibited excellent degradation rate and mineralization efficiency on SMX in 60 min, which exceeded 93.15% and 31.96%, respectively. Besides, its degradation rate constants was 1.68 times higher than that of the CuFe2O4/PMS system. The enhanced performance could be mainly ascribed to the efficient synergistic activation of PMS by two components: I. the successful dispersion of CuFe2O4 on N-rGO and the interaction between them exposed more Fe3+-O2- and Cu2+-O2- active sites via decreasing size and aggregation of CuFe2O4 particles; II. the supported N-rGO supplied extra CO, C–OH and C–NC active groups, resulting in a large number of π electrons; III. the pyrrole N formed by further doping of N could activate the π electrons and reduce the energy barrier of electron transfer. The abundant active groups and sites and excellent electron transfer ability co-accelerate the production of active species. Specifically, surface-bound radical (•OH, SO4•–) and singlet oxygen 1O2 played a dominant role according to ESR and quenching tests. Furthermore, M-O-C binding site between two components enhanced catalyst stability and reduced metal leaching, leading to its availability on reusability in the 5 cyclic experiments. Lastly, CuFe@NG/PMS system also possessed a strong application ability in actual aquatic environment for SMX treatment.

Heat-Induced Magnetic Transition for Water Electrolysis on NiFeN@NiFeOOH Core-Shell Assembly.

The overpotentials of electrochemical oxygen evolution reaction (OER) inherently originate from high electron transfer barriers of the redox couple driven water oxidation. Here, we propose a heat-induced magnetic transition strategy to reduce the spin-related electron transfer barriers. Coupling heat into electrochemical OER on a ferro-antiferromagnetic core-shell NiFeN@NiFeOOH, the heat-induced ferro-to-paramagnetic transition for NiFeN core at 55 °C and antiferro-to-paramagnetic transition for NiFeOOH shell at 70 °C significantly accelerate and accordingly achieve a cascaded Ni2+/Ni3+ driven water oxidation reaction. In addition, paramagnetic Niδ+ (δ ≥ 3) in NiFeN@NiFeOOH can thermochemically react with water to produce oxygen. The heat-induced magnetic transition concomitantly triggers the electrochemical redox couple driven water oxidation and the thermochemical water oxidation due to that heat-induced paramagnetic spin reduces the barriers of electricity driving the spin flipping. Our findings offer new insights into constructing the heat-electricity coupling water splitting.

Reconstructing bridging carbon atoms (from sp3-C to sp2-C) of pyrolytic N-doped carbon to enhance oxygen reduction reaction

The development of new regulation strategy for constructing functional carbon skeletons is a standing challenge for oxygen reduction reaction (ORR). Herein, the locally ordered graphene microcrystals with suitable N-sites derived from glucose are synthesized under the assistance of low melting point zinc molten salt. Utilizing the structural features of graphene microcrystals (“house of cards” model), the work function of carbon skeleton is reduced after inducing the conversion of bridging sp3-C to bridging sp2-C (ratio of sp2-C to sp3-C increases from 3.75 to 7.41). The lower work function of locally ordered microarchitectures decreases the long-range electron transfer barrier in outer-Helmholtz plane. And the synergy between pyridinic N and graphitic N is beneficial for enhancing short-range electron transfer process in inner-Helmholtz plane. After rearrangement of carbon skeletons, the half-wave potential can increase from 0.846 V to 0.874 V, and the HO2– by-product yield decreases from 31.5 % to 6.9 %. Furthermore, the discharge voltage of locally ordered microarchitecture (1.31 V) at 10 mA cm−2 can surpass the commercial Pt/C (1.25 V) in Zn-air battery devices. In brief, it provides a new direction of structure design for carbonaceous catalysts.

Asymmetric Coupled Dual‐Atom Sites for Selective Photoreduction of Carbon Dioxide to Acetic Acid

AbstractPhotocatalytic reduction of CO2 to value‐added liquid fuels is a promising approach to alleviate the global energy and environmental problems. However, highly selective production of C2+ products from CO2 reduction reaction (CO2RR) is very difficult because of the sluggish CC coupling reaction. An asymmetric coupled heteronuclear photocatalyst is designed to overcome this limitation. The new catalyst contains single atoms of nickel and cobalt loaded on titanium dioxide. It exhibits an impressive 71% selectivity for acetic acid. The experimental data and theoretical calculations reveal that the Ni and Co single atom sites not only significantly lower the energy barrier of electron transfer in photocatalysis but also efficiently promote the CC coupling toward CH3COOH. The high activity of such a heteronuclear catalyst system will shed light on the future development of effective materials for CO2RR.

Controllable interface engineering of g-C3N4/CuS nanocomposite photocatalysts

The rational fabrication of an efficient photocatalyst with optimal interface engineering remains a huge challenge for the enhancement of photocatalytic perpformance. Herein, a sequence of multidimensional nanocomposites with different spatial interfaces, including point, and line or face-contact surface are controllable designed by horizontal growing diverse dimensional (0D, 1D,2D and 3D) copper sulfide (CuS) on 2D graphitic-carbon nitride (g-C 3 N 4 ) nanosheets. Physical and photochemical measurements demonstrate that the formation of an extraordinary 2D/2D face-to-face contact interface can not only enhance the specific surface area, visible light utilization, and photo-excited charge separation efficiency, but also elevate the density and lifetime of photo-generated carriers. The results of ultraviolet photoemission spectroscopy (UPS) and density functional theory (DFT) calculation also confirm that charge transfer tends to occur in face-to-face contact. Among the types of nanocomposites considered, 2D/2D g-C 3 N 4 /CuS has the smallest electron transfer barrier (Ф Be ) between active species, thereby displaying the maximum photocatalytic apparent rate constant, which is about 12 times larger than that of pristine g-C 3 N 4 . Most importantly, this work systematically investigates the relationship between microscopic interface structure and photocatalytic activity from the perspective of the optical, and electrical and energy levels, providing a new insight on the rational design of desired interface engineering towards efficient photocatalysts. • 2D/xD g-C3N4/CuS nanocomposites with different spatial interfaces were fabricated. • 2D/2D g-C3N4/CuS nanocomposite displays the optimal photocatalytic performance. • The concentration, lifetime and separation-efficiency of photogenerated carriers were tested. • The energy barrier between active species and catalysts was analyzed by UPS and DFT. • The photocatalytic mechanism of 2D/2D g-C3N4/CuS nanocomposites is proposed.

Activating Pd nanoparticles via the Mott-Schottky effect in Ni doped CeO2 nanotubes for enhanced catalytic Suzuki reaction

The eco-friendly and reusable heterogeneous Pd catalyst is an attractive alternative to the homogeneous Pd catalyst in the Suzuki reaction. However, the relatively low activity of heterogeneous Pd catalyst has become a major obstacle to its practical application. Herein, we construct the Mott-Schottky junctions at the interface between the CeO2 semiconductors and the supported Pd metals. Furthermore, the Ni dopants are introduced into the CeO2 lattices, thereby increasing the difference of Fermi level between CeO2 and Pd and further reducing the barrier of directional electron transfer from CeO2 to Pd. Meanwhile, the electronic structure of each element in the Pd/Ce1-xNixO2-δ is reconstructed by adjusting the Ni/Ce atomic ratio, so that the oxygen vacancy sites and the Ni sites act as electronic donors to induce the transfer of free electrons to the Pd. As a result, the electron-rich Pd/Ce0.9Ni0.1O2-δ catalysts exhibit high catalytic activity with a turnover frequency (TOF) value of 34,743 h−1 in Suzuki reactions.

DFT calculations of double vacancies MoS2 catalyzing water gas shift reaction: S vacancies as electron bridge promote electron transfer to H2O and CO molecules

The poor activity of molybdenum disulfide (MoS2) basal plane is the key scientific problem to limit efficient hydrogen production. In this paper, MoS2 with single (VS-MoS2) and double sulfur vacancy (VS, S-MoS2) have been constructed and used for water gas shift reaction (WGSR). Results show that the adsorption energy of VS, S-MoS2 for CO molecule is −1.43 eV, which is 28.6 times and 1.1 times than original MoS2 and VS, S-MoS2, respectively. The energy barrier of the rate-determining step in the association mechanism of VS, S-MoS2 is 1.78 eV, which is 21% lower than pristine MoS2. S vacancies are active sites for CO and H2O adsorption. The delocalized electrons enrichment in S vacancies break the electron transfer barrier between the surface and molecules. Sulfur vacancies as medium make electrons continuously transferred to CO and H2O molecules.