A Hybrid Photo-Electro Catalytic Conversion of Carbon dioxide Using CuO-MgO Nanocomposite

Reducing carbon dioxide (CO2) into fuels accompanied by renewable resources has been under research since it helps to decrease CO2 levels in the atmosphere. The most suited source is solar energy which is generous and sustainable. In this aspect, photocatalysis (PC) and photo electrocatalysis (PEC) are favorable methods to utilize solar energy for CO2 reduction to carbonaceous fuels. A PEC system is more efficient than a PC system because of the ability to separate photogenerated holes and electrons for higher efficiency. The photo-electrochemical CO2 reduction reaction (PEC-CO2RR) can be considered as an artificial photosynthetic system that stores solar energy and stabilizes CO2 levels in the atmosphere. Here CuO�MgO nanocomposite (NC) is used for the effective PEC reduction of CO2 into viable carbonaceous fuels. A simple and scalable sol�gel process was used for synthesizing the CuO�MgO NC. The synthesized NC�s structural, morphological and elemental analysis was performed using XRD, Raman spectroscopy, SEM and EDX. Optical properties were evaluated using UV spectroscopy. The electrochemical and PEC analysis was carried out to study the catalytic behavior of CuO�MgO towards CO2 reduction by the cyclic voltammetry method. The CuO�MgO NC exhibited significantly improved PEC-CO2RR performance compared to electrochemical reduction alone. Moreover, the CuO�MgO NC displayed high structural stability and durability, which benchmark its potential towards PEC reduction to CO2 into carbonaceous fuels.This work was carried by the NPRP11S-1221-170116 from the Qatar National Research Fund (a member of Qatar Foundation). The statements made herein are exclusively the accountability of the authors.Scopu

Tailored fabrication of iridium nanoparticle-sensitized titanium oxynitride nanotubes for solar-driven water splitting: Experimental insights on the photocatalytic-activity-defects relationship

Understanding the photocatalytic-activity-defects relationship of titanium oxynitride nanotubes (TiON-NTs) is important for tailoring their photocatalytic performance. Herein, we fabricated highly ordered and vertically aligned nanotube arrays of TiON-NT-functionalized with iridium nanoparticles denoted as (Ir/TiON-NTs) for solar-driven water splitting. Positron annihilation lifetime spectroscopy (PALS) and variable-energy positron annihilation spectroscopy (VEPAS) were performed to quantify the vacancy-type defects of Ir/TiON-NTs relative to TiON-NTs and TiO2-NTs. The results display that the Ir/TiON-NTs exhibit abundant defects such as small nitrogen vacancies, larger size vacancy clusters, and small voids. The obtained photocurrent density of the Ir/TiON-NTs (11.3 mA cm-2) is about 3.97, 5, and 11.89 times higher than that of Ir/TiO2-NTs, TiON-NTs, and TiO2-NTs, respectively. The Mott-Schottky analysis revealed the highest significant negative shift in the band potential and the lowest donor density of Ir/TiON-NTs compared to its counterparts. This result is attributed to the unique structural and compositional merits of Ir/TiON-NTs despite the abundant defects, which delay the charge recombination and improve the photocatalytic activity. The presented study may open new frontiers on engineering the defects of metal oxynitrides with metal-based catalysts for photocatalytic applications.This work is made possible by NPRP Grant no. NPRP 7-485-1-091 from the Qatar National Research Fund (a member of Qatar Foundation). The statements made herein are solely the responsibility of the authors