Adsorption Of Carbon Monoxide Research Articles

Electrical and work function-based chemical gas sensors utilizing NC3 and graphene combination

Research has been conducted on the potential practical uses of heterostructures made of graphene and carbon nitride (NC3) following their successful synthesis. The remarkable gas sensing properties of these 2D nanosheets have captured significant interest, attributed to distinctive electronic characteristics and exceptional surface-to-volume ratio that are resulted from combination of NC3 and graphene. In this study, we present a detailed analysis of electronic and structural features of pristine NC3 and graphene (PG), and their in-plane heterostructures using first-principles density functional theory. Our investigation utilizes the B3LYP and dispersion-corrected van der Waals (vdW) functional WB97XD, along with 6-311G (d, p) basis set. Our findings indicate that the nanosheets we anticipated exhibit robust structural stability, characterized by a desirable cohesive energy. Furthermore, we observed a gradual increase in the bandgap as the concentration of N–C in the nanosheets increases. Additionally, we investigated the adsorption characteristics of these heterostructures towards toxic gas molecules such as SO2 and CO. Among the studied heterostructures, GNC3I demonstrated higher adsorption energy (Eads), with values of approximately −0.283 and −0.491 eV when exposed to SO2 and carbon monoxide gas molecules respectively. Electronic characteristics, including LUMO and HOMO energy values, energy gap (Eg) between HOMO and LUMO, work function, Fermi level, and conductivity, underwent notable modifications upon SO2 gas adsorption over nanosheets, except for PG. However, these parameters remained relatively unchanged following carbon monoxide adsorption. Natural bond orbital (NBO) and Mulliken charge analysis demonstrates that there is a transfer of charge from gas molecules to nanosheets. Although nanosheets exhibit slightly higher adsorption energy (Eads) values for CO gas compared to SO2 gas, various assessments, including molecular electrostatic potential (MEP) mapping, electronic properties, and charge transfer (CT) analysis, suggest that these nanosheets are superior sensors for detecting SO2 gas rather than carbon monoxide gas molecules.

Adsorption study of CO and O2 on Au5-x-yAgxCuy [x, y = 1, 3] trimetallic nanoclusters

In present study, we focus on adsorption of CO and O2 gases over different trimetallic nanocluster. Among all trimetallic nanoclusters, copper occupied four coordinated sites and found to be nearly planer. The adsorption of carbon monoxide (CO) at these four coordinated sites drastically changes the structure of all the trimetallic nanoclusters. The adsorption trend of CO followed by all trimetallic nanoclusters is copper, gold and silver respectively. The anomalous behaviour arises due to the relativistic effect in the case of gold. The relativistic effect destabilizes the d-orbital and s-orbital. The destabilized d-orbital enhances the pi-back bonding. Unlike CO, the O2 adsorption at four coordinated Cu-sites does not bring as drastic changes in the geometry of the nanocluster as it in the case of CO adsorption at 4-coordinated Cu-site. In contrast, CO adsorbs on these nanoclusters as one atom on top of another (μ1η1-atop mode), whereas O2 exhibits three types of bonding-bridging mode, atop mode (- μ2η2 or μ2η1 - bridging mode or μ1η1-atop mode).

Influence of alumina on the performance of Ag/ZnO based catalysts for carbon dioxide hydrogenation

We study silver-zinc oxide type catalysts with and without the addition of alumina and perform structural analysis and activity tests for the hydrogenation of carbon dioxide. Adding alumina has a dispersing effect on the zinc oxide without structurally altering the silver phase. An alumina-surface enriched ZnO/Al2O3 phase is observed with an increased surface reducibility. Ag/ZnO has a high selectivity towards carbon monoxide (63 ± 12 %) and methane (24 ± 3 %) and low selectivity towards methanol (13 ± 0.5 %). Operando infrared (SSITKA-FTIR) and mass spectrometric product detection indicate methane formation via an adsorbed carbon monoxide (COads) intermediate. The selectivity changes gradually with increasing alumina content, up to 80 ± 3 % toward methanol, and 20 ± 4 % carbon monoxide without methane detection, combined with a tripling of the space time yield to 0.65 ± 0.02mmolMeOH*gcat-1*h−1 at 250 °C and 30 bar. Kinetic analysis suggests that the selectivity change originates from hindering the CO-pathway, while the formate pathway leading to methanol remains active.

Revealing the differences in CO oxidation activity of Fe-CeO2, Fe2O3, and CeO2 using operando CO2-DRIFTS-MS: Carbonate species and desorption process

The carbonate on the catalyst surface is the key factor limiting carbon monoxide (CO) oxidation activity. However, the relationship between different carbonate species and surface oxygen species is not clear. In this paper, Fe-CeO2, Fe2O3, and CeO2 catalysts prepared by aerosol method are selected as the research target, and operando DRIFTS-MS is used as the main characterization method. Fe-CeO2 has good redox properties resulting in the best CO oxidation activity (350°C) and CO2 selectivity (98 %). Operando DRIFTS-MS results indicate that surface M=O species play a crucial role in the catalyst's activity, demonstrating the ability to react with CO at low temperatures. Notably, a high concentration of M=O facilitates the formation of monodentate carbonate (vas(CO32−)) (vas(CO32−) decomposes at 100°C). With increasing temperature, CeO and M-O-Ce also react with CO and produce M-Ov-Ce (oxygen vacancy). CO adsorption on M2+-O22− or M sites to form vas(OCO) or vs(OCO). The decomposition temperature of vs(OCO) exceeds that of vas(CO32−) significantly, and its presence serves as the crucial step in the oxidation of CO. The above conclusions reveal the relationship between surface carbonate and oxygen, and provide a theoretical basis for regulating the surface structure of catalysts.

Interactive impacts of organic-inorganic modifiers on surface characteristics of Cu+-doped activated carbon for stable CO-adsorptive separation from CO2

Conventional Cu+-doped activated carbon (C) materials are problematic in carbon monoxide (CO)-selective adsorption from carbon dioxide (CO2) due to their CO2-friendly surface basicity and microporosity. In this study, boehmite (AlOOH) film modified-carbon composite (AlC) was hydrothermally synthesized to dope with 30 wt% Cu+ ions by the impregnation-calcination method. The functional hydroxyl groups of Boehmite behaved as metallic anchoring sites for better Cu+ ion dispersion, enhancing the CO adsorption uptake to 38.84 cm3/g at 25 °C and ∼ 100 kPa in isotherm analysis. Additionally, the improved Lewis acidity of AlC surface interface together with pore widening impact reduced the CO2 uptake to 14 cm3/g, around half that of Cu+-doped activated carbon, by undergoing Lewis acid-acid repelling interaction between boehmite film and CO2. However, to address rapid oxidation of Cu+ ions in the hygroscopic AlC structure, iron (II) chloride (FeCl2) surface modification on the Cu+-doped AlC composite created a Fe3+-Cu+ bimetallic interface with high Cu+ immobilization, enriching the CO adsorption stability to 92 % even after 30 day-air exposure. Noticeably, pre-complexation of FeCl2 with thiourea (NH2CSNH2) before its dispersion over the doped Cu+ ions led to distinct Cu+ stabilization mechanisms without bimetallic redox interaction. This involves developing auto-redoxable iron (II) sulfides as barrier coatings for Cu+ species against oxidation and raising the Cu2+ reducibility via cyanide-ligands of thiourea. These combined preservation effects for Cu+ ions ensured CO adsorption stability of 91 %, underlining higher CO adsorption uptake (39.38 cm3/g) and CO/CO2 selectivity (67.49 at 0.2 kPa and 3.09 at ∼ 100 kPa) than modification effects of boehmite and FeCl2.

Synergistic removal of NO and CO in industrial waste gas by Fe-modified Cu/TiO2 catalysts: The synergistic effect of metal oxides interaction

NH3-based selective catalytic reduction (NH3-SCR) combined with carbon monoxide (CO) catalytic oxidation is a productive way to synergistically remove nitrogen oxides (NOx) and CO from industrial waste gas. Catalyst is the undoubtedly centerpiece of the synergistic removal technology, which has aroused tremendous attention. Herein, in this investigation a variety of Cu/TiO2 catalysts modified by various metal oxides were prepared by impregnation method, and the excellent synergistic removal performance of Fe-modified Cu/TiO2 catalyst was observed. The Cu/TiO2 catalyst with a 7 wt% Fe doping amount exhibited the highest NO and CO removal efficiency (86 % for NO at 300 °C and over 98 % for CO from 300 ∼ 400 °C). Through a series of characterization techniques, it was discovered that Cu and Fe oxides interacted to evenly distribute them throughout the surface of TiO2 support, resulting in smaller particle size and abundant variable valence species (Cu+/Cu2+ and Fe2+/Fe3+) to enhance the redox performance of the catalysts. Moreover, the creation of additional surface chemisorbed oxygen, the adsorption of NO and CO, and the improvement of surface acidity were all facilitated by the electron transfer between various Cu and Fe species. In addition, in-situ diffuse reflectance infrared transform spectroscopy (in situ DRIFTS) results revealed the interaction between NH3-SCR and CO oxidation. This study proposes a viable approach to develop efficient catalysts for the synergistic removal of NO and CO in industrial applications.

The Electrode/Electrolyte Interface Study during the Electrochemical CO2 Reduction in Acidic Electrolytes.

Electrochemical CO2 Reduction (CO2R) in acidic electrolytes has gained significant attention owing to higher carbon efficiency and stability than in alkaline counterparts. However, the proton source and the role of alkali cations for CO2R are still under debate. By using rotating ring disk electrode and surface-enhanced infrared absorption spectroscopy, we find that a neutral/alkaline environment at the interface is necessary for CO2R even in acidic electrolytes. We also confirm that water molecules, rather than protons serve as the proton source for CO2R. Alkali cations in the outer Helmholtz plane activate H2O and promote the desorption of adsorbed carbon monoxide. Additionally, the solvated CO2, or CO2(aq), is the actual reactant for CO2R. This study provides a deeper understanding of the electrode/electrolyte interface during CO2R in acidic electrolytes and sheds light on further performance improvement of this system.

Study of carbon monoxide adsorption on the α- and γ-graphyne nanosheets for the sensor applications

Recently, graphyne-based gas sensors have drawn a lot of interest. One kind of graphene with acetylene bonds connecting its hexagons is graphyne. In this study, the density functional theory (DFT) method was used to investigate the physical parameters of the surface adsorption of carbon monoxide on the [Formula: see text]- and [Formula: see text]-graphyne nanosheet, taking into account van der Waals (vdW) interactions through the use of the SIESTA computational code. CO molecule adsorbed and optimized in two vertical and horizontal states from the side of carbon and oxygen atoms, at different distances and sites relative to the graphyne sheet. After optimization and finding the adsorption energy, the best adsorption sites, equilibrium distance of the molecule from the surface, electronic structure, charge transfer rate, and bandgap changes were calculated. It was observed that the changes in the electronic structure after the adsorption of CO molecule are insignificant and the [Formula: see text]- and [Formula: see text]-graphyne nanosheets remained zero-gap and narrow-gap semiconductors, respectively. The adsorption of CO molecule on the [Formula: see text]- and [Formula: see text]-graphyne nanosheets is physisorption. The results show that the [Formula: see text]-graphyne nanosheet has a good potential for adsorbing and detecting CO molecules and sensor applications.

Constructing CO-immune water dissociation sites around Pt to achieve stable operation in high CO concentration environment

The serious problem of carbon monoxide (CO) poisoning on the surface of Pt-based catalysts has long constrained the commercialization of proton exchange membrane fuel cells (PEMFCs). Regeneration of Pt sites by maintaining CO scavenging ability through precise construction of the surface and interface structure of the catalyst is the key to obtaining high-performance CO-resistant catalysts. Here, we used molybdenum carbide (MoCx) as the support for Pt and introduced Ru single atoms (SA-Ru) at the Pt-MoCx interface to jointly decrease the CO adsorption strength on Pt. More importantly, the MoCx and SA-Ru are immune to CO poisoning, which continuously assists in the oxidation of adsorbed CO by generating oxygen species from water dissociation. These two effects combine to confer this anode catalyst (SA-Ru@Pt/MoCx) remarkable CO tolerance and the ability to operate stably in fuel cell with high CO concentration (power output 85.5 mW cm−2@20,000 ppm CO + H2 – O2), making it possible to directly use the cheap reformed hydrogen as the fuel for PEMFCs.

Experimental and density functional theory study of the gas sensing property of Pt and Au doped WS2 to partial discharge gas CO in air switchgear

This work aims to investigate the detection performance of WS2 and its doped gas sensitive materials for carbon monoxide (CO), one of the most important characteristic gases of partial discharge in air switchgear.Its accurate monitoring can be an effective evaluation of the operating condition of air switchgear. Three gas-sensitive materials were synthesized using the hydrothermal method: WS2, Pt-WS2, and Au-WS2. The materials were characterized through XRD, SEM, and XPS, followed by an evaluation of their sensing performance for CO gas. The findings revealed that the gas sensitivity of WS2 was significantly enhanced through doping with Pt and Au. At a CO concentration of 10 ppm, the response sensitivity of the Pt-WS2 sensor reached 4.03, while that of the Au-WS2 sensor was measured at 2.68—both representing an increase by a factor of 3.52 compared to intrinsic WS2 sensors. Moreover, the response recovery time for the Au-WS2 sensor was found to be 20–30 s faster than that observed in Pt-WS2 sensors. The mechanisms underlying the enhancement in CO adsorption on WS2 due to Pt and Au doping were investigated based on density functional theory calculations encompassing band structure analysis, density of states assessment, adsorption distance measurement, and adsorption energy evaluation. This study posits that both Pt-WS2 and Au-WS2 can be used for the detection of partial discharge gas CO in air switchgear.

Stabilized Cu0 -Cu1+ dual sites in a cyanamide framework for selective CO2 electroreduction to ethylene

Electrochemical reduction of carbon dioxide to produce high-value ethylene is often limited by poor selectivity and yield of multi-carbon products. To address this, we propose a cyanamide-coordinated isolated copper framework with both metallic copper (Cu0) and charged copper (Cu1+) sites as an efficient electrocatalyst for the reduction of carbon dioxide to ethylene. Our operando electrochemical characterizations and theoretical calculations reveal that copper atoms in the Cuδ+NCN complex enhance carbon dioxide activation by improving surface carbon monoxide adsorption, while delocalized electrons around copper sites facilitate carbon-carbon coupling by reducing the Gibbs free energy for *CHC formation. This leads to high selectivity for ethylene production. The Cuδ+NCN catalyst achieves 77.7% selectivity for carbon dioxide to ethylene conversion at a partial current density of 400 milliamperes per square centimeter and demonstrates long-term stability over 80 hours in membrane electrode assembly-based electrolysers. This study provides a strategic approach for designing catalysts for the electrosynthesis of value-added chemicals from carbon dioxide.

The Electrostatic Stimulation of Adsorbed Carbon Monoxide Oxidation on Pt in Aqueous Acidic Electrolytes

The oxidation of adsorbed carbon monoxide on Pt electrodes, CO(ads)|Pt, in aqueous electrolytes ranks among the most studied reactions in electrocatalysis both from theoretical[1]and experimental viewpoints.[2][3] Much of the interest in this electron transfer process stems from the role CO(ads) plays as an impurity that affects adversely the operation of H2|O2 fuel cells. Consensus appears to have been reached regarding the role of adsorbed hydroxyl, OH.(ads) in controlling the activation and ultimate oxidation of CO(ads). The present contribution illustrates the use of electrochemical stimulation techniques developed in our laboratory[4] to explore new aspects of this process not as yet unveiled by the use of more conventional methods. As described in our earlier publications,[4,5] electrode stimulation refers to changes in the rates of heterogeneous electron transfer processes involving adsorbed species induced by modifications in the electrostatic potential in the solution immediately adjacent to the electrode generated by the passage of current between an electrode placed very close to the working electrode, WE, polarized at constant potential, and a second electrode far away from it. The electrochemical cell used for these experiments consisted of a glass tube covered at each end with custom-made Teflon caps and, thus, similar in design to that described by Qi et al.[4] Experiments were performed in Ar-purged 0.1 M H2SO4 involving CO adsorbed at saturation coverages on polycrystalline Pt, polarized at EWE = 0.8 V, a potential very close to the onset of CO(ads) oxidation with a Au disk electrode placed directly above it working as a stimulating electrode, SE, i.e. face to face configuration. Shown in Fig. 1 are plots of the current flowing through the SE (red), iSE and iWE (black) (see Left Panel) and their expanded views during stimulation (Middle Panel) and CO full oxidation (Right Panel), respectively. As shown in the middle panel in this figure. the passage of a negative iSE, elicits a positive iWE ascribed to CO oxidation, which persists even when iSE turns positive, until the end of the stimulation process (see Right Panel), which takes several seconds. In brief, a single stimulation lasting 140 ms can trigger the full oxidation of the entire adsorbed CO layer in CO|Pt over a subsequent period of ca. 4 s. The most likely explanation for this unique effect may be found in the formation of adsorbed OH. on sites previously covered with CO, as the CV of bare Pt would strongly suggest, which will promote the subsequent oxidation of CO(ads), a process that will propagate through the entire Pt surface. Further support for this mechanism was provided by an experiment in which the WE potential was stepped down to 0.4 V immediately after the stimulation was applied, which stopped virtually instantaneously the further oxidation of CO(ads). Experiments are now in progress to image the surface of the CO|Pt electrode during and after the stimulation to monitor in real time the rates of propagation and to provide a more details theoretical model to account for this phenomenon. References 1 Gao, W.; Mueller, J.E.; Jiang, Q.; Jacob, T. Angew. Chem. Int. Ed. 2012, 51, 9448 –94522 Scott, S.B.; Kibsgaarda, J.; Vesborga, P.C.K.; Chorkendorff, I. Electrochim. Acta 2021, 374, 1378423 Scott, S.B.; Kibsgaarda, J.; Vesborga, P.C.K.; Chorkendorff, I. Electrochim. Acta 2021, 374, 1378444 Han, Q.; Georgescu, N. S.; Gibbons, J.; Scherson, D. Electrochim. Acta 2019, 325, 1349575 Heer, A.S.; Mantelli, H; Han, Q.; Georgescu, N. S.; Scherson, D. in preparation. Acknowledgement Support for this work provided by NSF, CHE-1808592.Fig. 1. Plots of iWE and iSE recorded for EWE = 0.8 V prior, during and following WE stimulation (see text for details) (Left Panel). The middle and right panels show expanded views of the data in the left panel during stimulation and CO full oxidation, respectively. Figure 1

Effect of Implanted Titanium, Vanadium or Chromium on Boron Nitride Surface for Increasing Carbon Monoxide Adsorption: Designing Gas Sensor for Green Chemistry Future

Effect of Implanted Titanium, Vanadium or Chromium on Boron Nitride Surface for Increasing Carbon Monoxide Adsorption: Designing Gas Sensor for Green Chemistry Future

Construction of H-Doped PdB Nanocrystals as Electrocatalysts to Modulate Formic Acid Oxidation.

The strong ligand effect in B-doped Pd-based (PdB) catalysts renders them a promising anode for constructing formic acid fuel cells (FAFCs) exhibiting high power density and outstanding stability. However, the enhancement of the oxidation barrier is unavoidable in this alloy system owing to the electron transfer (ET) from B to Pd. In this study, a hydrogen doping strategy is employed to open charge freedom in PdB compounds and boost their formic acid oxidation reaction (FAOR) activity by suppressing the ET process. The resulting hydrogen-doped PdB (PdBH) exhibits an ultrahigh mass activity of up to 1.2A mg-1 Pd, which is 3.23 times that of the PdB catalyst and 9.55 times that of Pd black. Detailed experimental and theoretical studies show that the interstitial hydrogen leads to enhanced orbital hybridization and reduced electron density around Pd. This optimized ligand effect weakens the carbon monoxide adsorption and increases the direct pathway preference of PdBH, resulting in its outstanding catalytic activity for the FAOR. The development of this high-performance hydrogen-doped PdB catalyst is an important step toward the construction of advanced light element co-doped metal catalysts.

Adsorbed Carbon Monoxide-Enabled Self-Terminated Au-Grafting on Pt6 Nanoclusters for Enhanced Methanol Electrooxidation.

The study presents the first example of an adsorbed carbon monoxide (CO) enabled self-terminated Au-grafting on triphenylphosphine (PPh3) stabilized Pt6 nanoclusters (NCs) (Pt6 (PPh3)4Cl5 NCs or Pt6 NCs). Adsorbed PPh3 ligands weaken the Pt-CO bond enabling the self-terminated Au-grafting on Pt6 NCs. The Au-grafted Pt6 NCs exhibit enhanced methanol electrooxidation (MOR) in acidic solutions. The surface is composed of a PtAu ensemble exhibiting enhanced MOR and CO tolerance due to the synergistic interaction of Pt with Au and PPh3. The hydrogen underpotential deposition (H-UPD) signal from a CO-covered surface reveals the existence of free-Pt sites on the PtAu ensemble causing higher MOR reactivity. The Au and PPh3 ensure electrocatalytic activity of the NCs, depriving of them at anodic potentials results in "a death-valley" trend.

Infrared Band Strengths of Dangling OH Features in Amorphous Water at 20 K

Infrared (IR) spectra of vapor-deposited amorphous water at low temperatures show two weak peaks at around 3720 and 3696 cm−1 assigned to free-OH stretching modes of two- and three-coordinated water molecules (so-called “dangling” OH bonds), respectively, on the ice surface. A recent JWST observation first succeeded in detection of a potential dangling OH feature at 3664 cm−1 for ices in molecular clouds, highlighting the importance of dangling OH bonds in interstellar ice chemistry. A lack of band strengths of these features at low temperatures restricts the quantification of dangling OH bonds from IR spectra, hindering development of a molecular-level understanding of the surface structure and chemistry of ice. Using IR multiple-angle incidence resolution spectrometry, we quantified the band strengths of two- and three-coordinated dangling OH features in amorphous water at 20 K as being 4.6 ± 1.6 × 10−18 and 9.1 ± 1.0 × 10−18 cm molecule−1, respectively. These values are more than an order of magnitude lower than band strengths of bulk-water molecules in ice and liquid water and are similar to those of H2O monomers confined in solid matrices. Adsorption of carbon monoxide with dangling OH bonds results in the appearance of a new broad dangling OH feature at 3680–3620 cm−1, with a band strength of 1.8 ± 0.1 × 10−17 cm molecule−1. The band strengths of dangling OH features determined in this study advance our understanding of the surface structure of interstellar ice analogs and recent IR observations of the JWST.

Toxic gas removal using transition metal-decorated Cyclo[18]carbon: A first principles prevision

Carbon monoxide (CO), nitric oxide (NO), and ammonia (NH3) are highly toxic gases that are hazardous to human health and the environment. This study dives into the examination of interaction mechanism between transition metal-decorated Cyclo[18]carbon or C18TM (TM = Ni, Pd, Pt) nanoclusters and aforementioned gas molecules. The analysis of structural, electronic, topological, spectroscopic, and sensing properties, uncovers significant findings. The computed adsorption energies exhibit highly negative values. Notably, a substantial sensing response is observed, particularly in the context of NO adsorption over C18Ni and CO adsorption over C18Pd nanoclusters. Employing the Quantum Theory of Atoms in Molecules (QTAIM), we discern the strength of each interaction. Raman spectra analyses provide additional details regarding the vibrational aspects of these interactions. Our Non-Covalent Interaction (NCI) study effectively elucidates the mechanisms underlying van der Waals interactions. Evidently, the longer recovery times observed in our calculations, owing to the highly negative adsorption energies with −2.31 eV being the most negative value for CO molecule over C18Pt nanocluster and −1.09 eV value for NO over C18Pd being the least, suggest that C18TM nanoclusters are better suited for gas removal applications rather than rapid-response sensors.

A Biphasic Strategy to Synergistically Accelerate Activation and CO Spillover in Formic Acid Oxidation Catalysis.

Developing highly efficient and carbon monoxide (CO)-tolerant platinum (Pt) catalysts for the formic acid oxidation reaction (FAOR) is vital for direct formic acid fuel cells (DFAFCs), yet it is challenging due to the high energy barrier of direct intermediates (HCOO* and COOH*) as well as the CO poisoning issues associated with Pt alloy catalysts. Here we present a versatile biphasic strategy by creating a hexagonal/cubic crystalline-phase-synergistic PtPb/C (h/c-PtPb/C) catalyst to tackle the aforementioned issues. Detailed investigations reveal that h/c-PtPb/C can simultaneously facilitate the adsorption of direct intermediates while inhibiting CO adsorption, thereby significantly improving the activation and CO spillover. As a result, h/c-PtPb/C showcases an outstanding FAOR activity of 8.1 A mgPt-1, which is 64.5 times higher than that of commercial Pt/C and significantly surpasses monophasic PtPb. Moreover, the h/c-PtPb/C-based membrane electrode assembly exhibits an exceptional peak power density of 258.7 mW cm-2 for practical DFAFC applications.

Adsorption and disproportionation of carbon monoxide on faceted-gold surfaces and edges

Localized surface plasmons (LSP) on faceted surfaces of gold nanoparticles enable carbon monoxide disproportionation to be driven at room temperature. In order to expand the known surfaces that catalyze this reaction, we explore the adsorption of carbon monoxide at top, long bridge, short bridge, and hole sites on gold (100), (110), (111), (211), and (311) faceted surfaces, as well as the reaction barriers for disproportionation at the lowest energy adsorption site on each surface and edges between two (311) surfaces and (100) and (110) surfaces. Generally, the less atomically dense, higher index facets promote both good adsorption and reactivity, and the edges show lower barriers for disproportionation. For most of the explored surfaces, adsorption directly on top of a gold atom is most favorable. The lowest activation energy for carbon monoxide disproportionation to amorphous carbon and carbon dioxide is predicted for two carbon monoxides adsorbed on top of atoms on the (311)/(311) edge.

The adsorption of CO gas on the surface of boron nitride incorporating 2D carbon allotropes: a DFT analysis

The adsorption properties of different Carbon allotropes (i.e., graphene, γ-graphyne, Mobius graphene, and R-graphyne) and their corresponding Boron (N) and Nitrogen (N) incorporated BCN nanostructures toward carbon monoxide (CO) gas are studied via density functional theory calculation. All the adsorbents demonstrated negative formation energies and real frequencies, i.e., can be synthesized and have dynamical stability. The adsorption energies have increased due to B and N incorporation, although still comparatively low for practical application. The highest adsorption energy with suitable recovery time is observed for the Mobius BCN structure, about −0.112 eV and 77.8 ps, respectively. Very nominal charge transfer is observed via Mulliken charge distribution and electrostatic potential map analysis. The changes in energy gap and electrical conductivity are observed due to CO adsorption.