Copper (I) oxide (Cu₂O) is an appealing semiconducting oxide with potential applications in various fields ranging from photovoltaics to biosensing. The precise control of size and shape of Cu₂O nanostructures has been an area of intense research. Here, the electrodeposition of Cu₂O nanoparticles is presented with precise size variations by utilizing ethylenediamine (EDA) as a size controlling agent. The size of the Cu₂O nanoparticles was successfully varied between 54.09 nm to 966.97 nm by changing the concentration of EDA in the electrolytic bath during electrodeposition. The large surface area of the Cu₂O nanoparticles present an attractive platform for immobilizing glucose oxidase for glucose biosensing. The fabricated enzymatic biosensor exhibited a rapid response time of <2 s. The limit of detection was 0.1 μM and the sensitivity of the glucose biosensor was 1.54 mA/cm². mM. The Cu₂O nanoparticles were characterized by UV-Visible spectroscopy, scanning electron microscopy and X-ray diffraction.

This study investigates the impact of different surfactants and dispersion techniques on the friction and wear behavior of WS₂ and MoS₂ nanoparticles additives in a Polyalphaolefin (PAO) base oil under boundary lubrication conditions. The nanoparticles were dispersed using Oleic acid (OA) and Polyvinylpyrrolidone (PVP) to investigate their impact on particle agglomeration. The size distribution of the dispersed nanoparticles in PAO was measured by dynamic light scattering. The nanoparticles treated using PVP resulted in the most stable particle size. Friction studies showed that nanoparticle agglomeration reduction and the homogeneity of the suspension did not significantly impact the friction reduction behavior of the lubricant. Reciprocating wear experiments showed that, for our test conditions, both WS₂ and MoS₂ nano additives exhibited maximum wear depth reduction (45%) when using the PVP surface treatment compared to base oil. The wear results confirmed the significance of minimizing agglomeration and promoting high dispersion in promoting favorable wear resistance under boundary lubricant conditions. Analysis of the wear surfaces showed that a tribofilm formation was the primary wear reduction mechanism for WS₂ particles treated by PVP while, in the case of MoS₂ treated by PVP, the mechanism was load sharing via particles rolling and/or sliding at the interface.

Copper (I) oxide (Cu₂O) is a promising photocathode for photoelectrochemical (PEC) water splitting. Here we study gold (Au) underlayer – Cu₂O composite photocathode for PEC water splitting. The dendritic gold nanostructures were successfully synthesized by varying reaction time during the electrodeposition process. The Cu₂O overlayer was electrodeposited onto Au nanostructures to form Au-Cu₂O photocathode. Scanning electron microscopy, X-ray diffraction, and electrochemical impedance spectroscopy were used to characterize the Au-Cu₂O photocathode. Additionally, the effect of morphology variation and possible growth mechanism of Au underlayer was evaluated. The photocurrent density of Au-Cu₂O photocathode reached up to 3 mA cm⁻², which is 2.5 times greater than that of control Cu₂O photocathode (1.25 mA cm⁻²) at 0 V vs RHE.