The use of solar energy to catalyze the photo-driven processes has attracted tremendous attention from the scientific community because of its great potential to address energy and environmental issues. In this regard, several attempts have been made by researchers to design and develop different materials with enhanced photocatalytic efficiencies. This Review comprehensively summarizes the recent reports on perovskite oxide based photocatalysts for organic pollutant degradation, water splitting, carbon dioxide conversion, and nitrogen fixation along with the basic understanding of involved mechanisms, current trends and advances in the field. The different design, synthesis, and development strategies have been discussed in detail to provide a comprehensive view of materials’ fabrication that influences their photocatalytic properties. Subsequently, the insights from recent reports on different perovskite oxide based materials, including simple oxides, mixed oxides, and layered perovskite oxides, are provided for the above-mentioned photocatalytic applications in a detailed manner. Finally, a summary of photocatalytic applications and a perspective on future research direction have been discussed. Based on the research progress in this field, it is highly anticipated that the photocatalytic systems, comprising perovskite oxide materials along with groundbreaking technologies for large-scale realization of these processes, can be established in the near future to address the energy and environment-oriented challenges.

Scheme 1. Different strategies and concepts employed in the design and development of photocatalysts based on a semiconductor, such as TiO 2 , and plasmonic NPs.

Clusters of diamond-phase carbon, known as nanodiamonds, exhibit novel mechanical, optical and biological properties that have elicited interest for a wide range of technological applications. Although diamond is predicted to be more stable than graphite at the nanoscale, extreme environments are typically used to produce nanodiamonds. Here we show that nanodiamonds can be stably formed in the gas phase at atmospheric pressure and neutral gas temperatures o100°C by dissociation of ethanol vapour in a novel microplasma process. Addition of hydrogen gas to the process allows in flight purification by selective etching of the non-diamond carbon and stabilization of the nanodiamonds. The nanodiamond particles are predominantly between 2 and 5 nm in diameter, and exhibit cubic diamond, n-diamond and lonsdaleite crystal structures, similar to nanodiamonds recovered from meteoritic residues. These results may help explain the origin of nanodiamonds in the cosmos, and offer a simple and inexpensive route for the production of high-purity nanodiamonds.

Photocatalytic materials for photocatalysis is recently proposed as a promising strategy to address environmental remediation. Metal-free graphitic carbon nitride (g-C 3 N 4 ), is an emerging photocatalyst in sulfate radical based advanced oxidation processes. The solar-driven electronic excitations in g-C 3 N 4 are capable of peroxo (O-O) bond dissociation in peroxymonosulfate/peroxydisulfate (PMS/PDS) and oxidants to generate reactive free radicals, namely SO 4•− and OH • in addition to O 2 •− radical. The synergistic mechanism of g-C 3 N 4 mediated PMS/ PDS photocatalytic activation, could ensure the generation of OH • radicals to overcome the low reductive potential of g-C 3 N 4 and fastens the degradation reaction rate. This article reviews recent work on heterojunction formation (type-II heterojunction and direct Z-scheme) to achieve the bandgap for extended visible light absorption and improved charge carrier separation for efficient photocatalytic efficiency. Focus is placed on the fundamental mechanistic routes followed for PMS/PDS photocatalytic activation over g-C 3 N 4 -based photocatalysts. A particular emphasis is given to the factors influencing the PMS/PDS photocatalytic activation mechanism and the contribution of SO 4 •− and OH • radicals that are not thoroughly investigated and require further studies. Concluding perspectives on the challenges and opportunities to design highly efficient persulfateactivated g-C 3 N 4 based photocatalysts toward environmental remediation are also intensively highlighted.

We have studied the magnetization of vertically aligned graphene nanoflakes irradiated with nitrogen ions of 100 KeV energy and doses in the range 10¹¹–10¹⁷ ions/cm². The non-irradiated graphene nanoflakes show a paramagnetic contribution, which is increased progressively by ion irradiation at low doses up to 10¹⁵/cm². However, further increase on implantation dose reduces the magnetic moment which coincides with the onset of amorphization as verified by both Raman and x-ray photoelectron spectroscopic data. Overall, our results demonstrate the absence of ferromagnetism on either implanted or unimplanted samples from room temperature down to a temperature of 5 K