CoOOH nanosheet electrodes: Simple fabrication for sensitive electrochemical sensing of hydrogen peroxide and hydrazine

Cobalt oxyhydroxide, CoOOH, nanosheets were prepared via a surface alkaline treatment of cobalt foil at room temperature without using templates and catalysts. The morphology, chemical composition and structures of the nanosheets were characterized by XRD, FTIR and Raman spectroscopy, FESEM and TEM. These oriented and nanostructured arrays can be used directly as electrodes, thus simplifying the electrode fabrication process, as well as offering advantages such as enhanced electrode-electrolyte contact area, minimum diffusion resistance and direct active material-current collector connection for fast electron transport. The electrode was used as an electrochemical sensor towards non-enzymatic detection of hydrogen peroxide and hydrazine in alkaline solution. The amperometric detection of H(2)O(2) and N(2)H(4) was carried out at low potential (0V and 0.1V). At 0.1V, the amperometric signals are linearly proportional to H(2)O(2) concentration up to 1.6mM (R(2)=0.995), showing a detection limit (S/N=3) of 40μM and a high sensitivity of 99μA mM(-1)cm(-2). For N(2)H(4), the amperometric signals are linearly proportional to concentration up to 1.2mM (R(2)=0.99), showing a detection limit (S/N=3) of 20μM and a high sensitivity of 155μA mM(-1)cm(-2) at 0.1V.

C@ZnO nanorod array-based hydrazine electrochemical sensor with improved sensitivity and stability

ZnO nanorod array grown directly on an inert alloy substrate has been modified with carbon by a simple immersion-calcination route and further used as the working electrode to construct a hydrazine sensor. The C@ZnO nanorod array-based sensor demonstrates a very high sensitivity of 9.4 muA muM(-1) cm(-2) and a low detection limit of 0.1 muM. The improved electrochemical properties are proposed to result from the synergy between the carbon layer and nanorod array, which can increase the ZnO electrocatalytic activity and promote the electron transport along the one-dimensional (1D) pathway, respectively. In particular, the carbon layer on ZnO nanorods also improves the sensor stability for successive usage due to the high chemical stability of carbon. The present study demonstrates the facile design of a promising electrode material for a hydrazine sensor and sheds light on the performance optimization of other electrochemical devices.

Understanding Supramolecular Interactions Provides Clues for Building Molecules into Minerals and Materials: a Retrosynthetic Analysis of Copper-Based Solids

The influence of non-covalent interactions on the crystal packing of molecules is well documented in the literature. Unlike molecular solids, crystal engineering of non-molecular solids is difficult to interpret as aggregation is complicated by the presence of neutral as well as ionic species and a range of forces operating, from weak hydrogen bonding to strong covalent interactions. In this perspective, we demonstrate for the first time the role of non-bonding interactions in the occurrence of oxide, hydroxide, or chloride linkages in oxides, hydroxychlorides, and chlorides of copper-based minerals and coordination polymers in terms of a mechanistic approach based on supramolecular retrosynthesis. The model proposed here visualizes the crystal nucleus as a supramolecular analogue of a transition state wherein appropriate tectons (chemically reasonable molecules) aggregate through non-bonding forces that can be perceived through well-known supramolecular synthons. The mechanistic approach provides chemical insights into the occurrence of different topologies and solid-state phenomena like polymorphism.