Energy CO2 Research Articles

Introducing yttrium into Pt-based intermetallic compounds induce electron perturbation and anti-oxidation for enhancing oxygen reduction activity and durability

Pt-based intermetallic compounds (IMCs) as competitive electrocatalysts for oxygen reduction reaction (ORR) still face problems of surface oxidation and transition metal (M) dissolution in harsh electrochemical environments. Here, we report a strategy to induce electronic perturbation in IMCs by introducing yttrium (Y) to further regulate Pt d-band filling and alloy stability, and Y-doped PtCo IMCs supported on π-electron-rich nitrogen-doped porous carbon (Y-PtCo/NPPC) are presented as a proof of concept. X-ray absorption fine structure (XAFS) reveals that the introduced Pt-O-Y configuration in PtCo IMCs allows the Pt 5d orbital occupancy to be increased, which enhances the anti-oxidation ability of Pt atoms and further stabilizes the internal Co atoms. Y-PtCo/NPPC exhibits satisfactory ORR activity with a high mass activity (MA) of 1.89 A mgPt-1 and is much higher than that of the Pt/C catalyst (0.19 A mgPt-1). In particular, the MA retention of up to 84.7 % is maintained after 30,000 cycles accelerated durability test (ADT), and the Co atom dissolution ratio decreased by 6.4 times compared to PtCo/NPPC. Impressively, the Y-PtCo/NPPC catalyst achieves a high peak power density (1.0 W cm−2) in proton exchange membrane fuel cell (PEMFC) (H2-air). Theoretical calculations have also demonstrated that the introduction of Y element shifts Pt d-band downward, weakening the adsorption of oxygen-containing intermediates. The improved stability stems from the enhancement of the vacancy formation energies of Pt and Co.

Computational descriptor for electrochemical currents of carbon dioxide reduction on Cu facets

Computation screening is crucial for designing efficient electrochemical catalysts for carbon dioxide (CO2R) reduction that produce valuable hydrocarbons and oxygenates. Herein, leveraging density functional theory calculations of the CO adsorption energy ΔECO on seventeen Cu terminations, we discover a strong linear correlation between ΔECO and the recently experimentally measured CO2R electrochemical currents (ACS Catal. 2022, 12, 11, 6578–6588). Examining the ab initio thermodynamics of the early critical intermediates CO*, COH*, and CHO*, we find that CO* → CHO* is the thermodynamically controlling step. Beyond the general CO adsorption energy that only shows a linear trend with CO2R activity, we show that the reaction free energy of CO* → CHO* is the descriptor for the overall CO2R activity for Cu facets, as it displays a volcano relationship with the experimental current. Importantly, we show that increasing the step and kink density of the Cu terminations not only enhances CO adsorption strength but also modulates the CO* → CHO* pathway, as respectively exemplified in the (941) and (741) facets. In addition, we explain that the high activity of (741) is due to its relatively low hydrogen evolution reaction activity compared with the other Cu surfaces.

Cu Based Dilute Alloys for Tuning the C2+ Selectivity of Electrochemical CO2 Reduction.

Electrochemical CO2 reduction is a promising technology for replacing fossil fuel feedstocks in the chemical industry but further improvements in catalyst selectivity need to be made. So far, only copper-based catalysts have shown efficient conversion of CO2 into the desired multi-carbon (C2+) products. This work explores Cu-based dilute alloys to systematically tune the energy landscape of CO2 electrolysis toward C2+ products. Selection of the dilute alloy components is guided by grand canonical density functional theory simulations using the calculated binding energies of the reaction intermediates CO*, CHO*, and OCCO* dimer as descriptors for the selectivity toward C2+ products. A physical vapor deposition catalyst testing platform is employed to isolate the effect of alloy composition on the C2+/C1 product branching ratio without interference from catalyst morphology or catalyst integration. Six dilute alloy catalysts are prepared and tested with respect to their C2+/C1 product ratio using different electrolyzer environments including selected tests in a 100-cm2 electrolyzer. Consistent with theory, CuAl, CuB, CuGa and especially CuSc show increased selectivity toward C2+ products by making CO dimerization energetically more favorable on the dominant Cu facets, demonstrating the power of using the dilute alloy approach to tune the selectivity of CO2 electrolysis.

Bond Dissociation Energy of CO2 with Spectroscopic Accuracy Using State-to-State Resolved Threshold Fragment Yield Spectra.

In this study, we present a precise determination of the bond dissociation energy of CO2 using state-to-state resolved threshold fragment yield spectra at a photoexcitation wavelength of around 92 nm. Our findings show that the bond dissociation energy of CO2, CO2 → CO + O, is 43976.12(15) cm-1 or 526.0714(18) kJ/mol. Furthermore, by incorporating our previously measured bond dissociation energies for CO and O2, we determined the dissociation energy of CO2 into C + O2 and the CO2 atomization energy (CO2 → C + O + O) to be 92309.73(21) and 133578.92(18) cm-1 or 1104.2699(25) and 1597.9592(22) kJ/mol, respectively. Thus, the bond dissociation energies of CO2 for all channels now have uncertainties of 0.2 cm-1 or 0.002 kJ/mol. These results serve as reference points for the enthalpies of C atom and CO and CO2 molecules and provide benchmarks for high-level ab initio quantum chemistry calculations.

Atomic Level Understanding of the Structural Stability and Catalytic Activity of Nanoporous Gold/Titania Cluster Inverse Catalysts at Ambient and High Temperatures.

Nanoporous gold (NPG) exhibits exceptional catalytic performance at low temperatures, but its activity declines at elevated temperatures due to structural coarsening. Loading metal oxide nanoparticles onto NPG can enhance its catalytic activity at high temperatures. In this work, we used NPG-supported titania nanoparticles as a model system (denoted as Ti2O4/NPG) to study their catalytic activity at ambient and high temperatures with CO oxidation as a probe reaction by density functional theory (DFT) calculation and ab initio molecular dynamics (AIMD) simulations. The possible factors that may affect the CO oxidation reaction pathways and energy profiles on the Ti2O4/NPG, such as oxygen vacancies; silver impurities; Mars-van Krevelen (MvK), Eley-Rideal (ER), or trimolecular Eley-Rideal (TER) mechanisms; and catalytic active sites, were comprehensively investigated. The results showed that reaction energy barriers on Ti2O4/NPG were not significantly decreased compared to the pristine NPG, indicating that their catalytic activities at ambient temperature were comparable. At the evaluated temperature (400 °C), the Ti2O4/NPG exhibited superior thermal stability and maintained its active sites, while the NPG reduced active sites due to surface coarsening. The strong oxide-metal interaction (SOMI) effect between the NPG and Ti2O4 nanoparticles is found to be a main factor for the high structural stability and catalytic activity at high temperatures.

Thermal properties and decomposition of perovskite energetic materials (C6H14N2) NH4 (ClO4)3

(C6N2H14) NH4 (ClO4)3 (DAP-4) have attracted an increasing focus recently as an ammoniumperchlorate-based molecular perovskite energetic material with outstanding features. Microscopy, variable temperature X-ray diffraction, in situ infrared spectroscopy, differential scanning calorimetry-thermogravimetry simultaneous thermal analysis coupled with infrared spectroscopy and mass spectrometry (DSC-TG/FTIR/MS) techniques were used to systematically investigate DAP-4 thermal properties from -40 °C to 550 °C. The results revealed that DAP-4 have two solid-solid crystallization phase transitions with a non-characteristic melting process. The generated activation energies of HCN, CO, CH2NH2, CO2 and NO2 gas products are all lower than the macroscopic decomposition's of DAP-4. This finding strongly proves that DAP-4 is easy to form these gas products during thermal stimulus. The two stages decomposition mechanism accompanying a large of CH2NH2 and NH2C2H4 gases and kinetic model of DAP-4 were proposed under the condition of high-purity argon gas. This study provides new insight into the in-depth and accurate description thermal decomposition mechanism of DAP-4 as a potential energetic material.

Energy‐Saving Hydrogen Production from Methanol Electrocatalysis Catalyzed by Molybdenum Phosphide/Nitrogen‐Doped Carbon Polyhedrons Supported Pt Nanoparticles

Comprehensive SummaryImproving the catalytic efficiency and anti‐poisoning ability of Pt‐based catalysts is very critical in methanol electrolysis technology for high‐purity hydrogen generation. Herein, the nitrogen‐doped carbon polyhedrons‐encapsulated MoP (MoP@NC) supported Pt nanoparticles were demonstrated to be effective for methanol electrolysis resulting from the combined advantages. The nitrogen‐doped carbon polyhedrons not only greatly enhanced the conductivity but also effectively prevented the aggregation of MoP to offer Pt anchoring sites. The electronic structure modification of Pt from their interaction reduced the adsorption energy of CO*, resulting in good CO‐poisoning resistance and accelerated reaction kinetics. Specifically, Pt‐MoP@NC exhibited the highest peak current density of 106.4 mA·cm–2 for methanol oxidation and a lower overpotential of 28 mV at 10 mA·cm–2 for hydrogen evolution. Energy‐saving hydrogen production from methanol electrolysis was demonstrated in the two‐electrode systems assembled by Pt‐MoP@NC which required a low cell voltage of 0.65 V to reach a kinetic current density of 10 mA·cm–2 on the glass carbon system, about 1.02 V less than that of water electrolysis.

Energy, Exergy, and Economic Analysis of a Low-Energy Consumption CO2 Capture System with Ionic Liquid [DEME][TF2N

Energy, Exergy, and Economic Analysis of a Low-Energy Consumption CO₂ Capture System with Ionic Liquid [DEME][TF₂N

Analysis of electronic properties and sensing applications in Graphene/BC3 heterostructures

Many research studies have been conducted into the applications of the heterostructures of graphene (Gr) and boron carbide (BC3) in real-world devices after they were synthesized successfully by researchers. Thanks to their unique electronic attributes and high surface-to-volume ratio, the above-mentioned two-dimensional nanosheets (NSs) such as have enjoyed the interest of many research groups and scientists. Within this piece of research, the electronic and structural attributes of pure Gr (PGr), pure BC3 (PBC3) and their in-plane heterostructures were investigated by employing the DFT along with the density functionals B3LYP and WB97XD. The results demonstrated that by increasing the concentration of the B-C, there was a gradual increase in the bandgap. Also, the structural stability of the NSs was good and the cohesive energy was favourable. In addition, the adhesion attributes of these NSs were investigated towards two toxic gasses, namely CO and SO2. Amongst the heterostructures, after exposure to CO and SO2, the adhesion energy of GBC3I was greater, which was approximately −0.487 eV and −0.229 eV, respectively. Following the adhesion of SO2 onto the surface of the NSs, apart from the PGr, there was a significant change in their electronic attributes such as conductance, workfunction, Fermi level, the LUMO, the HOMO and the bandgap. However, following the adhesion of CO, the above-mentioned attributed remained almost the same. Based on the NBO and Mulliken charge analysis, there was a charge transport from the gasses to the NSs. Despite the fact that the adhesion energies for CO were relative higher than the adhesion energies for SO2for the NSs, the analysis of the MEP maps, the charge transport and the electronic attributes demonstrated that the NSs can be used as promising nanosensors for the detection of SO2 rather than CO.

Theoretical study of adsorption of gas (CO, CO2, NH3) by metal (Au, Ag, Cu)-doped single-layer WS2.

The adsorptions of gas (CO, CO2, NH3) by metal (Au, Ag, Cu)-doped single layer WS2 are studied by density functional theory. The doping of metal atoms makes WS2 behave as n-type semiconductors. The final adsorption sites for CO, CO2, and NH3 are close to the atomic sites of the doped metal. The adsorptions of CO and NH3 gases on Cu/WS2, Ag/WS2, and Au/WS2 are dominated by chemisorption. The doped metal atoms enhance the hybridization of the substrate with the gas molecular orbitals, which contributes to the charge transfer and enhances the adsorption of the gas with the material surface. The adsorptions of CO and NH3 on Cu/WS2 and Ag/WS2 allow favorable desorption in a short time after heating. The single-layer Cu/WS2 is proved to have the potential to be used as a reliable recyclable sensor for CO. This work provides a theoretical basis for developing high-performance WS2-based gas sensors. In this paper, the adsorption energy, electronic structure, charge transfer, and recovery time of CO, CO2, and NH3 in the doped system have been investigated based on the CASTEP code of density functional theory. The exchange correlation function used is the Perdew-Burke-Ernzerhof (PBE) generalized gradient approximation (GGA). The TS (Tkatchenko-Scheffler) dispersion correction method was used to involve the effects of van der Waals interaction on the adsorption energies for all adsorption system. The ultrasoft pseudopotentials are chosen and the plane-wave cut-off energies are set to 500eV. The k-point mesh generated by the Monkhorst package scheme is used to perform the numerical integration of the Brillouin zone and 5 × 5 × 1k-point grid is used. The tolerances of total energy convergence, maximum ionic force, ionic displacement, and stress component are 1.0 × 10-5eV/atom, 0.03eV/Å, 0.001Å, and 0.05 GPa, respectively.

Water-gas shift activity of atomically embedded transition-metals on AlN support: A DFT investigation

Single-Atom Catalysts (SACs) have piqued the interest of the global research community due to their remarkable catalytic activity in some key industrial chemical reactions. Herein, the catalytic efficacy of transition metals (TMs) embedded AlN (M@AlN; M = Ni, Pd, Pt, Cu, Ag, Au) are examined towards water–gas shift (WGS) reaction by employing first-principles-based, spin-polarized, van der Waals corrected, density functional theory (DFT) calculations. The strong interactions between M-atoms and AlN substrate (at Al-d site) and the higher diffusion barrier of M-atoms over AlN specifies the steadfast-stability of M@AlN. Further, the abstemious interplay between reactants (CO, OH, H2O, CO + OH and CO + H2O) corroborates the potency of M@AlN in harbouring the reactants. Then, to contemplate the activity of M@AlN towards WGS reaction, a well-established formate mechanism and a fairly novel OH-assistive mechanism, were considered. Predominantly, the OH-assistive mechanism determined to be more favourable than the formate mechanism. Precisely, the Au@AlN and Cu@AlN systems are deemed as most active and competent SACs for WGS reaction via OH-assistive mechanism with the required activation energy (Ea) of rate determining step (RDS) reckoned to be 0.14 eV and 0.21 eV, respectively. Moreover, the linearity of Ea with co-adsorption energy of CO–OH molecules (Eads(CO + OH)) and d-band centre (εd) substantiate the findings. Also, the comparison between Ea and reaction energy (ER) certifies the workability of Au/Cu@AlN towards WGS reaction. Wherefore, the investigation under discussion connotes Au/Cu@AlN can be a cogent, practicably applicable SACs for WGS reaction.

Metal-Organic Framework-Derived Au-Doped In2O3 Nanotubes for Monitoring CO at the ppb Level.

Achieving selective detection of ppb-level CO is important for air quality testing at industrial sites to ensure personal safety. Noble metal doping enhances charge transfer, which in turn reduces the detection limit of metal oxide gas sensors. In this work, metal-organic framework-derived Au-doped In2O3 nanotubes with high electrical conductivity are synthesized by pyrolysis of the Au-doped metal-organic framework (In-MIL-68) as a template. Gas-sensing experiments reveal that the detection limit of 0.2% Au-doped In2O3 nanotubes (0.2% Au, mass fraction) is as low as 750 ppb. Meanwhile, the sensing material shows a response value of 18.2 to 50 ppm of CO at 240 °C, which is about 2.8 times higher than that of pure In2O3. Meanwhile, the response and recovery times are short (37 s/86 s). The gas-sensing mechanism of CO is uncovered by in situ DRIFTS through the reaction intermediates. In addition, first-principles calculations suggest that Au doping of In2O3 significantly enhances its adsorption energy for CO and improves the electron transfer properties. This study reveals a novel synthesis pathway for Au-doped In2O3 nanotubular structures and their potential application in low concentration CO detection.

Regulate the adsorption of oxygen-containing intermediates to promote the reduction of CO2 to CH4 on Ni-based catalysts

The introduction of oxophilic metals can enhance the selectivity of CO2 reduction reactions (CO2RR) by modulating the adsorption of oxygen-associated active substances on the catalyst surface. Alloying lanthanide atoms into metals has been shown to improve CH4 selectivity by breaking the linear relationship between the adsorption energies of CO* and HxCO*. In this work, a series of oxophilic transition metals (Fe, Mo, Co, Mn) are introduced to explore the influence on the CO2RR. DFT results demonstrate that the doping of oxophilic metals regulates the adsorption strength between the catalyst surface and intermediates, thereby affecting the CH4 and H3COH pathways. Notably, COOH* formation is enhanced on Ni surfaces, leading to increased H3COH production. Ni-Fe and Ni-Mo exhibit significant H3CO* and CO2* binding energies, which reduces the barrier for H3CO*. Meanwhile, the bond energy of M−O is higher than that of C-O in H3CO*, promoting the generation of CH4. The addition of Co and Mn makes the desorbed of HCOOH smaller than the hydrogenation energy barrier, which accelerates the synthesis of formic acid. This research provides a new pathway for the development of inexpensive and resource-rich catalysts.

Effect of Metal d Band Position on Anion Redox in Alkali-Rich Sulfides.

New energy storage methods are emerging to increase the energy density of state-of-the-art battery systems beyond conventional intercalation electrode materials. For instance, employing anion redox can yield higher capacities compared with transition metal redox alone. Anion redox in sulfides has been recognized since the early days of rechargeable battery research. Here, we study the effect of d-p overlap in controlling anion redox by shifting the metal d band position relative to the S p band. We aim to determine the effect of shifting the d band position on the electronic structure and, ultimately, on charge compensation. Two isostructural sulfides LiNaFeS2 and LiNaCoS2 are directly compared to the hypothesis that the Co material should yield more covalent metal-anion bonds. LiNaCoS2 exhibits a multielectron capacity of ≥1.7 electrons per formula unit, but despite the lowered Co d band, the voltage of anion redox is close to that of LiNaFeS2. Interestingly, the material suffers from rapid capacity fade. Through a combination of solid-state nuclear magnetic resonance spectroscopy, Co and S X-ray absorption spectroscopy, X-ray diffraction, and partial density of states calculations, we demonstrate that oxidation of S nonbonding p states to S2 2- occurs in early states of charge, which leads to an irreversible phase transition. We conclude that the lower energy of Co d bands increases their overlap with S p bands while maintaining S nonbonding p states at the same higher energy level, thus causing no alteration in the oxidation potential. Further, the higher crystal field stabilization energy for octahedral coordination over tetrahedral coordination is proposed to cause the irreversible phase transition in LiNaCoS2.

Utilizing the Hartree-Fock Method to Analyze Carbon Dioxide Molecule

The determination of the ground state of the carbon dioxide molecule is conducted through matrix Hartree-Fock computations for a polyatomic molecule. Utilization of basis sets is implemented to achieve a precision that approaches the sub-μ Hartree of the CO<sub>2</sub> molecule for the energy levels. Utilizing a 28s14p14d14f atom-centered and a 24sl0plld bond-centered Gaussian basis set, the upper limit for the Hartree-Fock ground state energy of CO<sub>2</sub> at its practical picture has been calculated, yielding a value of -187.125408 Hartree. Utilizing our knowledge in diatomic molecules, we approximate the precision of this measurement to fall within 5-6 μ Hartree. The current computations offer a methodology to assess the precision of different basis sets frequently utilized in molecular self-consistent field investigations. These basis sets encompass STOJG, 4-31G, 6-31G, 6-31G(3d), 6-31IG, 6-311+G(3d0, D95, and D95V+(3d)), alongside cc-pVDZ, uug-cc-pVDZ, cc-pVTZ, and aug-cc-pVTZ, which have been proposed for the purpose of investigating electron correlation. We have recently performed calculations on the CO1 ground state at the nuclear geomevy employed in the presenl work using the basis sets proposed by Dunning and co-workers and designated cc-pVQZ. aupcc-pVQZ, cc-pVSZ and nupcc-pVSZ. The estimated basis set truncation emrs for these sets are 0.00371, 0.003 19, 0.00047 and 0.00039 Hartree respectively.

A comparative DFT study of CO and NO capture by copper- and titanium-functionalized SiC and GeC monolayers

In this work, the interactions of NO and CO molecules with silicon carbide (SiC) and germanium carbide (GeC) graphene-like nanosheets, functionalized with titanium and copper atoms, are comparatively studied through density-functional calculations. The results indicate that NO and CO molecules are only slightly adsorbed on the pristine carbide nanosheets. Also, the copper and titanium adatoms are chemisorbed on the monolayers, leading to stable functionalized carbide nanosheets. These adatoms greatly enhance the binding energies of CO and NO. In particular, the titanium-functionalized GeC monolayers display the highest adsorption energies for CO and NO and also the largest changes in their work functions upon molecule adsorption, indicating that they could be useful for trapping or detecting these molecules.

A single Mn atom supported by a boron-vacancy in a BN monolayer: An encouraging catalyst for CO oxidation

Single-atom catalysts (SACs) are known for their exceptional activity, primarily attributed to the abundance of low-coordinated metal atoms, which enable efficient activation of robust chemical bonds, including CO bonds. In this work, we explore the prospective utilization of a specific SAC, isolated Mn atoms supported on Boron nitrogen (Mn/BN), for CO oxidation. By analyzing the adsorption/co-adsorption energies of CO, O2, O2+CO, and 2CO, we create a set of screening criteria and conduct a comparative analysis of the chemical processes involved in CO oxidation. The Langmuir-Hinshelwood (LH), Eley-Rideal (ER), termolecular Langmuir-Hinshelwood (TLH) and termolecular Eley-Rideal (TER) mechanisms are investigated. Results indicate the ER and LH mechanisms feature pronouncedly lower barrier of 0.33 and 0.41 eV, respectively, for the rate-limiting step, than those of the TLH (0.72 eV) and TER (3.00 eV) mechanisms, suggesting that the ER and LH mechanisms are favorable at normal temperature. This study offers valuable insights that can inform future developments in the design of low-temperature CO oxidation processes utilizing SACs.

Study on the kinetic characteristics and control steps of gas production in coal spontaneous combustion under the oxidation path

The low-temperature oxidation of coal involves multiple gas production paths including desorption, pyrolysis and oxidation. These paths interfere with each other, resulting in unclear kinetic characteristics of CO and CO2 production in coal oxidation and incomplete mechanism of gas production. Therefore, this paper proposed a method that can effectively exclude the effects of desorption and pyrolysis on gas production and adopted this method to explore the kinetic characteristics of CO and CO2 production under different paths. Besides, with the aid of microscopic characterization methods, the kinetic steps controlling gas production and the mechanism of gas production were analyzed. The experimental results demonstrate that the proposed method can effectively eliminate the effects of desorption and pyrolysis, and can obtain the kinetic characteristics of gas production under the oxidation path that can reflect the intrinsic characteristics of low-temperature oxidation of coal. Based on the difference method, the activation energies of CO and CO2 produced under the oxidation path are 59.49 kJ/mol and 60.09 kJ/mol, which activation energies are almost the same, suggesting that CO and CO2 are likely to be produced from the same precursor. The gas production in low-temperature oxidation is a process in which methylene groups in coal react with oxygen to generate oxygen-containing intermediates which then decompose to produce CO and CO2. The reaction of methylene groups with oxygen is the control step of gas production kinetics in coal spontaneous combustion, resulting in the same apparent activation energies of CO and CO2 production in the stable phase under the oxidation path.

Study on Pd-MoTe2 monolayer for adsorption and sensing of air decomposition products in air-insulated switchgear

Detecting characteristic decomposition components has become a popular method for assessing the operational stability of air-insulated switchgear. This paper investigates the adsorption and sensing properties of a Pd-modified MoTe2 (Pd-MoTe2) for two common defective gases, namely, NO2 and CO, in air-insulated switchgear and employs the first-principles density functional theory (DFT) to conduct the analysis. According to the findings, Pd has a preference for doping in the TMo site on the MoTe2 monolayer, with a binding energy (Eb) of −2.240 eV. The Pd-MoTe2 monolayer exhibits effective adsorption of NO2 and CO, with both molecules chemisorbed. The adsorption energies (Ead) for NO2 and CO are −1.307 eV and −1.550 eV, respectively. Furthermore, there is an evident reduction of the band gap for the Pd-MoTe2 upon adsorbing NO2, decreasing the resistance value. In short, the Pd-MoTe2 monolayer has shown great promise as a gas sensor, laying the groundwork for improving power system stability.

A comparative DFT study on the adsorption properties of lithium batteries thermal runaway gases CO, CO2, CH4 and C2H4 on pristine and Au doped CdS monolayer

The thermal runaway gases, such as CO, CO2, CH4, and C2H4, will leak from the battery electrolyte when lithium batteries in extreme discharge or thermal runaway conditions. The structural properties, differential charge density (DCD), density of state (DOS), gas adsorption properties, desorption time, work function and front-orbit theory calculation of pristine and Au doped CdS monolayer are explored and compared by first-principle calculation. The adsorption energy of CO, CO2, CH4 and C2H4 on the surface of Au–CdS are –0.89 eV, –0.40 eV, –0.14 eV and –0.77 eV, respectively. After doping, the adsorption type of CO and C2H4 are chemical type. Partial density of states shows that the gas molecules react with doped precious metal atoms. The adsorption ability of Au–CdS can be ranged as CO>C2H4>CO2>CH4. C2H4 on the surface of Au–CdS can desorb within 10 s at room temperature. As a result, Au–CdS exhibits tremendous prospective application as CO or C2H4 gas sensor. This study demonstrates that the adsorption and sensing properties of CdS monolayer can be improved effectively by the introduction of precious metal.