Tuning MXenes Towards Their Use in Photocatalytic Water Splitting

Finding appropriate photocatalysts for solar-driven water(H_(2)O)splitting to generate hydrogen(H_(2))fuel is a challenging task,particularly when guided by conventional trial-and-error experimental methods.Here,density functional theory(DFT)is used to explore the MXenes photocatalytic properties,an emerging family of two-dimensional(2D)transition metal carbides and nitrides with chemical formula M_(n+1)X_(n)T_(x),known to be semiconductors when having T_(x)terminations.More than 4,000 MXene structures have been screened,considering different compositional(M,X,T_(x),and n)and structural(stacking and termination position)factors,to find suitable MXenes with a bandgap in the visible region and band edges that align with the water-splitting half-reaction potentials.Results from bandgap analysis show how,in general,MXenes with n=1 and transition metals from group III present the most cases with bandgap and promising sizes,with C-MXenes being superior to N-MXenes.From band alignment calculations of candidate systems with a bandgap larger than 1.23 eV,the minimum required for a water-splitting process,Sc_(2)CT_(2),Y_(2)CT_(2)(T_(x)=Cl,Br,S,and Se)and Y_(2)CI_(2)are highlighted as adequate photocatalysts.

cell2mol:encoding chemistry to interpret crystallographic data

The creation and maintenance of crystallographic data repositories is one of the greatest data-related achievements in chemistry.Platforms such as the Cambridge Structural Database host what is likely the most diverse collection of synthesizable molecules.If properly mined,they could be the basis for the large-scale exploration of new regions of the chemical space using quantum chemistry(QC).Yet,it is currently challenging to retrieve all the necessary information for QC codes based exclusively on the available structural data,especially for transition metal complexes.To overcome this limitation,we present cell2mol,a software that interprets crystallographic data and retrieves the connectivity and total charge of molecules,including the oxidation state(OS)of metal atoms.We demonstrate that cell2mol outperforms other popular methods at assigning the metal OS,while offering a comprehensive interpretation of the unit cell.The code is made available,as well as reliable QC-ready databases totaling 31k transition metal complexes and 13k ligands that contain incomparable chemical diversity.