Prediction of bimetal embedded in two-dimensional materials for CO2 reduction electrocatalysis with a new integrated descriptor.

CO2 reduction catalysis plays an important role in the process of converting harmful exhaust gas into useful fuels. However, the product complexity and the difficult hydrogenation in critical steps make it difficult to find a suitable catalyst for CO2 reduction. In this work, we report homo/hetero bimetal embedded in two-dimensional materials for electrocatalysis and discovered a new descriptor. We chose ß12-borophene accommodating two transition metal atoms for efficient CO2RR as a model system. We found that MnCo and VV systems are promising for CO2 reduction with good stability and high selectivity over HER. Through least absolute shrinkage and selection operator (LASSO) regression, we discovered a new integrated descriptor containing the spin moment of the metals and the descriptor is linked with the performance of the first step of CO2 hydrogenation. The MnCo system could catalyze a C1 process with low free energy change of the rate determining step. The VV system could also conduct the C2 process with low free energy change of the rate determining step. Bader charge analysis shows the ability of the borophene substrate to provide or hold electrons. This work demonstrates homonuclear and heteronuclear biatomic catalysts with high activity for CO2RR.

Design of Heterostructures of MXene/Two-Dimensional Organic Frameworks for Na-O2 Batteries with a New Mechanism and a New Descriptor.

Na-O2 batteries are promising candidates to replace Li-O2 batteries for their excellent performance. However, the charge overpotential of Na-O2 batteries is usually too high. In this work, we designed combinations of MXene and a two-dimensional organic framework for Na-O2 batteries. The results show that the Ti2CO2/Cu-BHT has low OER and ORR overpotentials of 0.24 and 0.32 V, respectively. Besides this, the conductivity and the adsorption energy to Na+ (Eads(Na+)) are promoted due to the charge transfer between layers. We also found that the OER and ORR overpotentials are negatively and positively correlated with Eads(Na+), respectively, where Ti2CO2/Cu-BHT has a moderate Eads(Na+) (-2.20 eV) and, therefore, has good performance. Moreover, a new mechanism called the Na encapsulation mechanism was proposed on a two-dimensional organic framework surface. Through least absolute shrinkage and selection operator (LASSO) regression, we found a new descriptor that consists of inherent properties that could help us screen better heterostructures for Na-O2 batteries.

Prediction of Dual-Doped Integrated CsPbBr3-CsPbCl3 Perovskite Heterostructure for Practical Photocatalytic Water Splitting with a New Descriptor.

Photocatalytic water splitting has always been a field where breakthroughs are expected to solve energy and environmental problems. However, current catalysts suffer from low activity in mismatched catalytic environments and high cost. Herein, we designed a series of integrated CsPbBr3-CsPbCl3 heterostructures to explore their catalytic capability. Based on extensive calculations, we discovered the inner connection between dopant atoms and the catalytic performance and proposed a new descriptor by applying the Least Absolute Shrinkage and Selection Operator (LASSO) analysis. After systematic screening, the CsPbBr3:Ni-CsPbCl3:Co system is found to be promising for single-catalyst overall water splitting under the same environment. Furthermore, a smaller bandgap that covers the redox potential of water splitting suggests the capability for photocatalysis. Besides, the CsPbBr3:Ni-CsPbCl3:Co system bulk-doped by Co could conduct the photocatalysis with better performance.

Predicted Optimal Bifunctional Electrocatalysts for the Hydrogen Evolution Reaction and the Oxygen Evolution Reaction Using Chalcogenide Heterostructures Based on Machine Learning Analysis of in Silico Quantum Mechanics Based High Throughput Screening.

Two-dimensional van der Waals heterostructure materials, particularly transition metal dichalcogenides (TMDC), have proved to be excellent photoabsorbers for solar radiation, but performance for such electrocatalysis processes as water splitting to form H2 and O2 is not adequate. We propose that dramatically improved performance may be achieved by combining two independent TMDC while optimizing such descriptors as rotational angle, bond length, distance between layers, and the ratio of the bandgaps of two component materials. In this paper we apply the least absolute shrinkage and selection operator (LASSO) process of artificial intelligence incorporating these descriptors together with quantum mechanics (density functional theory) to predict novel structures with predicted superior performance. Our predicted best system is MoTe2/WTe2 with a rotation of 300°, which is predicted to have an overpotential of 0.03 V for HER and 0.17 V for OER, dramatically improved over current electrocatalysts for water splitting.

Potential Applications of Heterostructures of TMDs with MXenes in Sodium-Ion and Na-O2 Batteries.

Na-ion batteries are viewed as the alternative to Li-ion batteries for similar electrochemical properties, while they always suffer from a low capacity. Na-O2 batteries are important due to their high energy density; however, they are usually limited by high overpotential. In this manuscript, 16 different heterostructures of TMDs with MXenes (bare and O-terminated case) are constructed and their potential in the application of sodium-ion batteries (SIBs) and Na-O2 batteries is explored. Among these structures, it is proved that only the heterostructures of VS2 with O-terminated MXenes could load five layers of Na+ ions, while the others will have a distortion when Na+ ions intercalate or diffuse in the interlayer or the second adsorption layer. The ultrasmall diffusion barrier of Na+ ion denotes that these structures have a fast charge/discharge speed, and the ultrasmall open circuit voltages (OCVs) of 0.18 and 0.21 V prove that they are promising candidates for SIBs. The ultralow overpotential 0.55 V/0.20 V for the ηORR/ηOER means that the O facet of the VS2/Ti2CO2 heterostructure also has a great potential in the application of Na-O2 batteries. These simulations prove that the heterostructures constructed by TMDs with MXenes have great potential in SIBs and Na-O2 batteries and are important for future battery design.