Possibility Of Direct Integration Research Articles

CO2 Conversion on Ligand‐Protected Au25 Nanoparticle: The Role of Structural Inhomogeneity in the Promotion of the Electrocatalytic Process

The possibility of direct integration with renewable electric sources adds more potential to the electrochemical method as a promising route for CO2 conversion. Previous experimental breakthrough reveals that Au25(SR)18− nanoclusters having 25 gold atoms and 18 protecting thiolate ligands can be utilized as catalysts for CO2 electroreduction to CO. The reason for its observed activity toward CO2 conversion is of fundamental importance that needs to be explained. Herein, the progress made in the first‐principles mechanistic studies of the reduction process is described. Contrary to long‐standing assumptions, the fully ligand protected version is not the active catalyst because of the weak adsorption of the relevant intermediates. Instead, the calculations based on computational hydrogen electrode method reveal that the reduction process is facilitated by a thermodynamically stable yet structurally inhomogeneous active site. This reaction center binds the intermediates in such a way that the process can occur at low overpotentials. The results point to the role of inhomogeneity in the surface region for this class of materials as a critical factor promoting the CO2 conversion process under electrochemical environment.

(Invited) Ligand Protected Au-Based Nanoclusters: A New Materials Domain for Efficient Electrochemical CO2 conversion with Broken Scaling Relationship

The possibility of direct integration with renewable electric sources adds more potential to the electrochemical method as a promising route for CO2 conversion. In our previous joint experimental-computational efforts, Au25(SR)18 - nanoclusters having 25 gold atoms and 18 protecting thiolate ligands was the first Au nanocluster identified and utilized as catalysts for CO2 electro-reduction to CO. Here, we present first principles-based method coupled with Poisson Boltzmann implicit solvation model to screen other known synthesized atomically precise nanostructures within this class of materials. We proposed a list of promising CO2 reduction catalyst which has not yet been explored in the field to the best of our knowledge. The existence of strong scaling relationship between the carbon containing intermediates in transition metal catalysts poses mechanistic limitation for optimization of CO2 reduction efficiency. In the case of the nanoclusters, we demonstrate that the covalent nature of the active site specifically stabilize the COOH intermediate breaking the pre-existing scaling relationship between COOH and CO binding energies on metals. Our results point to the broader application of covalent aided active site in complex electrochemical processes. We anticipate that our study may hasten the expansion of the domain of materials for CO2 reduction electro-catalysts into a new realm of ligand protected gold-based nanoclusters.

Nanoscale Lateral Field-Emission Triode Operating at Atmospheric Pressure

A nano-triode fabricated out of doped silicon-on-insulator material is demonstrated. Low turn-on voltages and the possibility of direct integration into existing silicon technology are but two of the advantages of these new devices. It is also possible to tune the current collected at the drain electrode by biasing the gate electrodes. The Figure depicts a scanning electron micrograph of the free-standing silicon nanostructure.