Two kinds of graphitic carbon nitride (g-C₃N₄) were synthesized through a pyrolysis process of urea or melamine. It is found that the obtained g-C₃N₄, as photocatalysts, can reduce CO₂ to organic fuels under visible light, and exhibit different photoactivity and selectivity on the formation of CH₃OH and C₂H₅OH. The product derived from the urea (denoted as u-g-C₃N₄) shows a mesoporous flake-like structure with a larger surface area and higher photoactivity for the CO₂ reduction than the non-porous flaky product obtained from melamine (denoted as m-g-C₃N₄). Moreover, using u-g-C₃N₄ as a photocatalyst can result in the formation of a mixture containing CH₃OH and C₂H₅OH, while m-g-C₃N₄ only leads to the selective formation of C₂H₅OH. The present interesting findings could shed light on the design of efficient, eco-friendly and convenient photocatalysts and the tuning of their photoreactivity in the field of sustainable light-to-energy conversion.

This perspective gives an overview of recent developments in heterogeneous photocatalytic CO₂ reduction for C1/C2 fuels production over semiconductors, which has been known for several decades as a potential feasible means to store intermittent solar energy and to recycle CO₂. In recent years, significant efforts have been made in order to further improve the photoactivity and the selectivity through developing novel photocatalysts and its CO₂ photoreduction reaction systems, which would be of great interest in the field of solar conversion and CO₂ resource utilization.

Anatase TiO₂ nanocrystals with {101}, {001} or {010} single facets of 90% level exposure were controllably synthesized from potassium titanate (PT) without fluorine and organic capping surfactants, and characterized by X-ray diffraction patterns (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), and fast Fourier transformation (FFT). The liquid-phase photocatalytic reduction (O₂˙⁻ generation) and oxidation (˙OH generation) activity orders of anatase TiO₂ facets are {001} > {101} > {010} upon removing facet synergetic effect and surface fluorine effect. UV-vis diffuse reflectance spectra (DRS) and photoluminescence (PL) spectra showed that absorbance edge order, and separation efficiency order of photoexcited holes and electrons are {001} > {101} > {010}, which explains the photocatalytic activity order well together with the atomic arrangement of different facets.

Chemical composition of secondary metabolites is of great importance for quality control of agricultural products. Black sesame seeds are significantly more expensive than white sesame seeds, because it is thought that black sesame seeds are more beneficial to human health than white sesame seeds. However, the differences in nutrient composition between black sesame seeds and white sesame seeds are still unknown. The current study examined the levels of different metabolites in black and white sesame seeds via the use of a novel metabolomics strategy. Using widely targeted metabolomics data, we obtained the structure and content of 557 metabolites, out of which 217 metabolites were identified, and discovered 30 metabolic pathways activated by the secondary metabolites in both black and white sesame seeds. Our results demonstrated that the main pathways that were differentially activated included: phenylpropanoid biosynthesis, tyrosine metabolism, and riboflavin metabolism. More importantly, the biomarkers that were significantly different between black seeds and white sesame seeds are highly related to the functions recorded in traditional Chinese medicine. The results of this study may serve as a new theoretical reference for breeding experts to promote the genetic improvement of sesame seeds, and therefore the cultivation of higher quality sesame varieties.