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The electrochemical reduction of CO2 (CO2RR) has the potential to allay the greenhouse gas effect while also addressing global energy challenges by producing value-added fuels and chemicals (mostly C2 molecules such as ethylene and ethanol). However, due to the complicated chemical pathways involved, achieving high selectivity and efficiency towards specific reduction products remains challenging. In fact, the design of more selective and efficient catalysts often relies on trial-and-error approaches, which are very time consuming and resource intensive. In response, driven by the inherent importance of CO adsorption energy in the conversion of CO2 into C2+ hydrocarbons and alcohols, we propose a two-step approach employing machine learning classification and regression algorithms to predict CO binding energies on CuM(111)/(100) (M = Al, Ti, V, Fe, Co, Ni, Zn, Nb, Mo, Ru, Pd, Ag, Cd, Sn, Sb, Hf, W, Ir, Pt, Au) bimetallic surfaces. Firstly, we assess the stability of each adsorption site by utilizing classification algorithms. Subsequently, focusing exclusively on the stable sites, we employ regression models to predict the adsorption energies of CO. Remarkably, by employing a Gradient Boosting Classifier for classification, together with a Gradient Boosting Regressor for regression, we predict CO binding energies with a high level of robustness and accuracy for Cu bimetallic alloys with up to 17% surface impurity concentrations. The accuracy of our models is demonstrated by F1 scores exceeding 96% and a mean square error below 0.05 eV² for the classification and regression parts, respectively. These remarkable results highlight the adaptability of our approach and its capability for efficiently screening Cu-based CO2RR electrocatalysts, enabling rapid evaluation of promising candidates for future in-depth explorations. [ABSTRACT FROM AUTHOR]

The optoelectronic properties of two-dimensional (2D) materials can be significantly influenced by charge transfer resulting from surface molecular adsorption. One noteworthy example is observed in WS2 monolayers, where the behavior undergoes an anomalous change when exposed to air, primarily due to the adsorption of oxygen molecules. While the acceptor nature of O2 is widely acknowledged as the underlying cause, the precise electron transfer mechanism remains in need of a comprehensive explanation at the atomistic level. Going beyond conventional charge population analysis, we develop an approach describing the process of molecular adsorption and surface charge transfer that relies on the formalism commonly adopted for charged defects in semiconductors. This method clearly identifies two key factors contributing to electron transfer upon O2 physisorption: the presence of sulphur vacancies and the intrinsic n-type nature of WS2. This approach provides an effective and general scheme to characterize the surface charge transfer in 2D materials exposed to a gas atmosphere. [ABSTRACT FROM AUTHOR]

Two‐dimensional (2D) materials as tungsten disulphide (WS2) are rising as the ideal platform for the next generation of nanoscale devices due to the excellent electric‐transport and optical properties. However, the presence of defects in the as grown samples represents one of the main limiting factors for commercial applications. At the same time, WS2 properties are frequently tailored by introducing impurities at specific sites. Aim of this review paper is to present a complete description and discussion of the effects of both intentional and unintentional defects in WS2, by an in depth analysis of the recent experimental and theoretical investigations reported in the literature. First, the most frequent intrinsic defects in WS2 are presented and their effects in the readily synthetized material are discussed. Possible solutions to remove and heal unintentional defects are also analyzed. Following, different doping schemes are reported, including the traditional substitution approach and innovative techniques based on the surface charge transfer with adsorbed atoms or molecules. The plethora of WS2 monolayer modifications presented in this review and the systematic analysis of the corresponding optical and electronic properties, represent strategic degrees of freedom the researchers may exploit to tailor WS2 optical and electronic properties for specific device applications. [ABSTRACT FROM AUTHOR]

The development of efficient CO2 capture and utilization technologies driven by renewable energy sources is mandatory to reduce the impact of climate change. Herein, seven imidazolium-based ionic liquids (ILs) with different anions and cations were tested as catholytes for the CO2 electrocatalytic reduction to CO over Ag electrode. Relevant activity and stability, but different selectivities for CO2 reduction or the side H2 evolution were observed. Density functional theory results show that depending on the IL anions the CO2 is captured or converted. Acetate anions (being strong Lewis bases) enhance CO2 capture and H2 evolution, while fluorinated anions (being weaker Lewis bases) favour the CO2 electroreduction. Differently from the hydrolytically unstable 1-butyl-3-methylimidazolium tetrafluoroborate, 1-Butyl-3-Methylimidazolium Triflate was the most promising IL, showing the highest Faradaic efficiency to CO (>95%), and up to 8 h of stable operation at high current rates (−20 mA & −60 mA), which opens the way for a prospective process scale-up. Room-temperature ionic liquids are increasingly investigated as electrolytes for electrocatalytic CO2 reduction thanks to their high intrinsic ionic conductivities, wide electrochemical potential windows, and high CO2 absorption capacities and solubilities. Here, seven imidazolium-based ionic liquids are investigated as electrolytes for the electrochemical conversion of CO2 to CO using a silver foil cathode, with their stability, co-catalytic effects, and varying selectivities elucidated. [ABSTRACT FROM AUTHOR]

Copper (Cu)-based materials for efficient CO2 conversion to adjustable syngas are reported. We employ an energy-efficient microwave-assisted route to synthesize copper/copper oxides with different structures and morphologies. The initial oxidation state of the copper on the surface significantly influences the performance of the materials in the CO2 reduction reaction (CO2RR). On the as-prepared material surface, a high content of Cu2O improves the selectivity toward CO and consequently the catalyzed CO2RR produce a syngas with a low H2/CO ratio, while the CuO performs poorly. In particular, Cu2O particles with a cubic shape show the highest selectivity for the CO formation. The superior catalytic activity of the Cu2O cubes for the CO2RR is attributed to the surface roughening under potential, which offers abundant electrochemically active sites and facilitates mass transport. [ABSTRACT FROM AUTHOR]

Bandgap engineering of semiconductor materials represents a crucial step for their employment in optoelectronics and photonics. It offers the opportunity to tailor their electronic and optical properties, increasing the degree of freedom in designing new devices and widening the range of their possible applications. Here, we report the bandgap engineering of a layered InSe monolayer, a superior electronic and optical material, by substituting In atoms with Ga atoms. We developed a theoretical understanding of I n 1 − x G a x S e stability and electronic properties in its whole compositional range ( x = 0 − 1 ) through first-principles density functional theory calculations, the cluster expansion method, and kinetic Monte Carlo simulations. Our findings highlight the possibility of modulating the InGaSe bandgap by ≈0.41 eV and reveal that this compound is an excellent candidate to be employed in many optoelectronic and photonic devices. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) materials as tungsten disulphide (WS 2 ) are rising as the ideal platform for the next generation of nanoscale devices due to the excellent electric-transport and optical properties. However, the presence of defects in the as grown samples represents one of the main limiting factors for commercial applications. At the same time, WS 2 properties are frequently tailored by introducing impurities at specific sites. Aim of this review paper is to present a complete description and discussion of the effects of both intentional and unintentional defects in WS 2 , by an in depth analysis of the recent experimental and theoretical investigations reported in the literature. First, the most frequent intrinsic defects in WS 2 are presented and their effects in the readily synthetized material are discussed. Possible solutions to remove and heal unintentional defects are also analyzed. Following, different doping schemes are reported, including the traditional substitution approach and innovative techniques based on the surface charge transfer with adsorbed atoms or molecules. The plethora of WS 2 monolayer modifications presented in this review and the systematic analysis of the corresponding optical and electronic properties, represent strategic degrees of freedom the researchers may exploit to tailor WS 2 optical and electronic properties for specific device applications., (© 2023 The Authors. Advanced Science published by Wiley-VCH GmbH.)