Chelation-Based Route to Aluminum-Free Layered Transition Metal Carbides (MXenes).

MXenes are of much interest because of their electrochemical, electronic, and surface chemical properties that arise from their structure and stoichiometry. The integrity and the nature of the terminal groups on the basal planes of MXene sheets depend strongly on the method used to etch the parent MAX (M = transition metal, A = Al, X = C, N, B) compound. Aluminum removal typically involves a high concentration of aqueous HF, HCl/LiF mixtures, or fluoride solutions of strong acids.

Stabilization of Dinuclear Rhodium and Iridium Clusters on Layered Titanate and Niobate Supports.

Atomically dispersed organometallic clusters can provide well-defined nuclearity of active sites for both fundamental studies as well as new regimes of activity and selectivity in chemical transformations. More recently, dinuclear clusters adsorbed onto solid surfaces have shown novel catalytic properties resulting from the synergistic effect of two metal centers to anchor different reactant species. Difficulty in synthesizing, stabilizing, and characterizing isolated atoms and clusters without agglomeration challenges allocating catalytic performance to atomic structure.

Soft chemistry of ion-exchangeable layered metal oxides.

Soft chemical reactions such as ion-exchange and acid-base reactions have been extensively investigated to synthesize novel metastable layered inorganic solids, to exfoliate them into individual nanosheets, and to re-assemble them as thin films and nanocomposite materials. These reactions proceed at relatively low temperature and enable the synthesis of a rich variety of structures by stepwise reactions. In recent years, the toolbox of soft chemical reactions has been utilized to rationally design and tailor the properties of functional layered transition metal oxides.