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Disposal of palm oil mill effluent (POME), which is highly polluting from the palm oil industry, needs to be handled properly to minimize the harmful impact on the surrounding environment. Photocatalytic technology is one of the advanced technologies that can be developed due to its low operating costs, as well as being sustainable, renewable, and environmentally friendly. This paper reports on the photocatalytic degradation of palm oil mill effluent (POME) using a BiVO4 photocatalyst under UV-visible light irradiation. BiVO4 photocatalysts were synthesized via sol-gel method and their physical and chemical properties were characterized using several characterization tools including X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), surface area analysis using the BET method, Raman spectroscopy, electron paramagnetic resonance (EPR), and UV-Vis diffuse reflectance spectroscopy (UV-Vis DRS). The effect of calcination temperature on the properties and photocatalytic performance for POME degradation using BiVO4 photocatalyst was also studied. XRD characterization data show a phase transformation of BiVO4 from tetragonal to monoclinic phase at a temperature of 450 °C (BV-450). The defect site comprising of vanadium vacancy (Vv) was generated through calcination under air and maxima at the BV-450 sample and proposed as the origin of the highest reaction rate constant (k) of photocatalytic POME removal among various calcination temperature treatments with a k value of 1.04 × 10−3 min−1. These findings provide design guidelines to develop efficient BiVO4-based photocatalyst through defect engineering for potential scalable photocatalytic organic pollutant degradation. [ABSTRACT FROM AUTHOR]

The large‐scale application of electrochemical reduction of CO2, as a viable strategy to mitigate the effects of anthropogenic climate change, is hindered by the lack of active and cost‐effective electrocatalysts that can be generated in bulk. To this end, SnO2 nanoparticles that are prepared using the industrially adopted flame spray pyrolysis (FSP) technique as active catalysts are reported for the conversion of CO2 to formate (HCOO−), exhibiting a FEHCOO− of 85% with a current density of −23.7 mA cm−2 at an applied potential of −1.1 V versus reversible hydrogen electrode. Through tuning of the flame synthesis conditions, the amount of oxygen hole center (OHC; SnO●) is synthetically manipulated, which plays a vital role in CO2 activation and thereby governing the high activity displayed by the FSP‐SnO2 catalysts for formate production. The controlled generation of defects through a simple, scalable fabrication technique presents an ideal approach for rationally designing active CO2 reduction reactions catalysts. [ABSTRACT FROM AUTHOR]

Active and cost‐effective catalyst materials are required for electrochemical CO2 reduction reactions (CO2RR) which, to date, are proving elusive. Here, the direct electrochemical conversion of CO2 to liquid products with a high overall Faradaic efficiency (FE) by utilizing a unique 3D, heterostructured copper electrode (referred as Cu sandwich) that is obtained via a simple two‐step treatment of commercially available copper foam is reported. The designed catalyst achieves an FE toward liquid products of >50% at an applied potential as low as −0.3 V versus reversible hydrogen electrode. The improved selectivity of the heterostructured Cu sandwich electrode at low overpotentials is attributed to the greater exposure of engineered Cu+/Cu2+ interfaces (present on composite nanowires) and higher oxygen vacancy defects. Moreover, the rationally designed heterostructures prevent the Cu2O species from being reduced during CO2RR enabling the catalyst to demonstrate enhanced CO2RR activity with prolonged stability. A 3D heterostructured copper electrode (Cu sandwich) for CO2 reduction reactions (CO2RR) is fabricated by a simple two‐step treatment of commercially available copper foam. The catalyst demonstrates a high selectivity toward ethanol and methanol production during CO2RR. The improved selectivity of the Cu sandwich can be explained by the presence of Cu+/Cu2+ interfaces and oxygen vacancy defects. [ABSTRACT FROM AUTHOR]

A TiO 2 /TiOF 2 composite has been synthesized through a hydrothermal method and characterized using X-ray diffraction, Raman spectroscopy, UV-vis diffuse reflectance, SEM-EDX, TEM, and N 2 adsorption-desorption isotherms. The percentage of exposed facet [001] and the composition of TiO 2 /TiOF 2 in the composite were controlled by adjusting the amount of HF and hydrothermal temperature synthesis. Three crucial factors in the photocatalytic conversion of methane to methanol, including the photocatalyst, electron scavenger (FeCl 2 ), and H 2 O 2 were evaluated using a statistical approach. All factors were found to have a significant impact on the photocatalytic reaction and exhibited a synergistic effect that enhanced methanol production. The highest methanol yield achieved was 0.7257 μmole h -1 g cat -1 . The presence of exposed [001] and fluorine (F) in the catalyst is believed to enhance the adsorption of reactant molecules and provide a more oxidative site. The Fenton cycle reaction between FeCl 2 and H 2 O 2 was attributed to reducing recombination and extending the charge carrier lifetime. Incorporating Ag into the TiO 2 /TiOF 2 catalyst results in a significant 2.2-fold enhancement in methanol yield. Additionally, the crucial involvement of hydroxyl radicals in the comprehensive reaction mechanism highlights their importance in influencing the process of photocatalytic methane-to-methanol conversion., Competing Interests: There is no conflict of interests existing in the manuscript submission, and it is approved by all of the authors for publication. All the authors listed have approved the manuscript to be enclosed., (This journal is © The Royal Society of Chemistry.)

Defect engineering of semiconductor photocatalysts is considered as an evolving strategy to adjust their physiochemical properties and boost photoreactivity of the materials. Here, hydrogenation and UV light pre-treatment of TiO 2 /SiO 2 composite with the ratio of 9 : 1 (9TiO 2 /1SiO 2 ) were conducted to generate Ti 3+ and non-bridging oxygen holes center (NBOHC) defects, respectively. The 9TiO 2 /1SiO 2 composite exhibited much higher photocatalytic water splitting than neat TiO 2 and SiO 2 as a consequence of the electronic structure effects induced by the defect sites. Electron paramagnetic resonance (EPR) indicated that hydrogenated and UV light pre-treated of 9TiO 2 /1SiO 2 boosted a higher density of Ti 3+ and NBOHC defect which could serve to suppress photogenerated electron-hole pair recombination and act as shallow donors to trap photoexcited electron. Overall, both defect sites in 9TiO 2 /1SiO 2 delivered advantageous characteristic relative to neat TiO 2 and SiO 2 with the finding clearly illustrating the value of defect engineering in enhancing photocatalytic performance., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

The large-scale application of electrochemical reduction of CO 2 , as a viable strategy to mitigate the effects of anthropogenic climate change, is hindered by the lack of active and cost-effective electrocatalysts that can be generated in bulk. To this end, SnO 2 nanoparticles that are prepared using the industrially adopted flame spray pyrolysis (FSP) technique as active catalysts are reported for the conversion of CO 2 to formate (HCOO - ), exhibiting a FE HCOO - of 85% with a current density of -23.7 mA cm -2 at an applied potential of -1.1 V versus reversible hydrogen electrode. Through tuning of the flame synthesis conditions, the amount of oxygen hole center (OHC; Sn≡O●) is synthetically manipulated, which plays a vital role in CO 2 activation and thereby governing the high activity displayed by the FSP-SnO 2 catalysts for formate production. The controlled generation of defects through a simple, scalable fabrication technique presents an ideal approach for rationally designing active CO 2 reduction reactions catalysts., Competing Interests: The authors declare no conflict of interest.