A green spark in electronics:Electrochemical innovations for a sustainable printed circuit board industry

Printed circuit boards (PCBs) are an integral part in our modern society. All of our tools, including cars, computers, microwaves and air-conditioning units among others, contain these vital components. PCBs use copper tracks to transfer electricity between the individual components. The current manufacturing process heavily relies on a top-down approach, where the substrate is first completely covered with copper and then all the undesired copper is selectively etched away. This is a highly wasteful process, generating large amounts of contaminated waste water containing dissolved copper and organics.In this dissertation, I propose two alternatives to reduce the environmental impact of the PCB industry. Firstly, an alternative approach for waste water treatment is proposed based on the oxygen reduction reaction towards hydrogen peroxide with a nitrogen-doped carbon electrocatalyst. The in situ generated hydrogen peroxide is used to oxidize organic pollutants directly. With this method, transportation costs for hydrogen peroxide are diminished, while the catalyst is made from abundant reagents. The second alternative is to alter the manufacturing process completely. Instead of the top-down approach, I propose a bottom-up one where the copper tracks are selectively plated were needed. This technique, already known in the industry, does relay on expensive palladium catalysts, reducing the economic viability. By changing the atomic composition of the catalyst, its effectiveness is increased while the costs were simultaneously diminished

Potential energy surfaces for Rh-CO from DFT calculations

We present potential energy surfaces for Rh-CO obtained from d. functional theory for two electronic states of Rh-CO. We have performed local spin-d. calcns. including relativistic as well as gradient corrections. The construction of a reasonably accurate atom-atom potential for Rh-CO is not possible. We were much more successful in constructing the potential energy surfaces by representing the potential as a spherical expansion. The expansion coeffs., which are functions of the distance between the rhodium atom and the carbon monoxide center of mass, can be represented by Lennard-Jones, Buckingham, or Morse functions, with an error of the fit within 10 kJ/mol. The potential energy surfaces, using Morse functions, predict that the electronic ground state of Rh-CO is 2S+ or 2D. This is a linear structure with an equil. distance of rhodium to the CO center of mass of 0.253 nm. The bonding energy is -184 kJ/mol. Morse functions predict that the first excited state is 3A'. This is a bent structure (?Rh-CO - 14 Deg) with an equil. distance of rhodium to the carbon monoxide center of mass of 0.298 nm. The bonding energy of this state is -60 kJ/mol. Both these predictions are in good agreement with the actual d. functional calcns. We found 0.250 nm with -205 kJ/mol for 2S+ and 0.253 nm with -199 kJ/mol for 2D. For 4A', we found 0.271 nm, ?Rh-CO = 30 Deg, with -63 kJ/mol. The larger deviation for 4A' than for 2S+ or 2D is a consequence of the fact that the min. for 4A' is a very shallow well. [on SciFinder (R)

Advances in Palladium-Catalyzed Cascade Cyclizations

The past decades in organic chemistry have witnessed significant improvements in synthetic efficiency as a result of considerable progress in cascade reactions, tandem reactions, and related one-pot processes. These methods are less time-consuming and produce less waste compared to the classical stepwise approach. However, cascade chemistry requires a more careful design and compatible reaction types for success. Palladium-catalyzed cross-coupling reactions, with their well understood multistep catalytic cycles, form a promising basis for the design of cascade reactions. Furthermore, they are compatible with a range of functional groups and can be combined with a range of secondary transformations. The resulting palladium-catalyzed cascade reactions have provided access to a plethora of complex small molecules of high medicinal relevance. This review provides an overview of the developments in palladium-catalyzed cascade reactions since 2011, classified according to the initiation, propagation, and termination steps comprising the palladium cascade reactions. This classification should assist the reader and may provide inspiration for the design of new cascade reactions. (Figure presented.)

Chemisorption theory of ammonia on copper

We present local-density-approximation calculations of ammonia adsorption on copper clusters of different sizes (6 to 18 atoms) modelling the (100) and (111) surface. Including for some of the copper atoms only one instead of eleven electrons explicitly in the calculation, did not always work satisfactorily. Comparison of adsorption energies for clusters of related geometry indicates a preference for onefold adsorption. This is due to the Pauli repulsion of the lone-pair orbital of ammonia with the copper 3d electrons. which is minimal for onefold adsorption. as well as an interaction with 4s electrons, which is most attractive in the onefold geometr

A membrane-free flow electrolyzer operating at high current density using earth-abundant catalysts for water splitting

Electrochemical water splitting is one of the most sustainable approaches for generating hydrogen. Because of the inherent constraints associated with the architecture and materials, the conventional alkaline water electrolyzer and the emerging proton exchange membrane electrolyzer are suffering from low efficiency and high materials/operation costs, respectively. Herein, we design a membrane-free flow electrolyzer, featuring a sandwich-like architecture and a cyclic operation mode, for decoupled overall water splitting. Comprised of two physically-separated compartments with flowing H(2)-rich catholyte and O(2)-rich anolyte, the cell delivers H(2) with a purity >99.1%. Its low internal ohmic resistance, highly active yet affordable bifunctional catalysts and efficient mass transport enable the water splitting at current density of 750 mA cm(−2) biased at 2.1 V. The eletrolyzer works equally well both in deionized water and in regular tap water. This work demonstrates the opportunity of combining the advantages of different electrolyzer concepts for water splitting via cell architecture and materials design, opening pathways for sustainable hydrogen generation