Novel photoelectrochemical 3D-system for water disinfection by deposition of modified carbon nitride on vitreous carbon foam.

Graphitic carbon nitride (GCN) is an optical semiconductor with excellent photoactivity under visible light irradiation. It has been widely applied for organic micropollutant removal from contaminated water, and less investigated for microorganisms' inactivation. The photocatalytic degradation mechanism using GCN is attributed to a series of reactions with reactive oxygen species and photogenerated holes that can be boosted by modifying its physical-chemical structure. This work reports a successful improvement of the overall photocatalytic and electrocatalytic activities of the pristine material by thermal and chemical modification by a copolymerisation synthesis method. The copolymerisation of dicyandiamide as a precursor with barbituric acid strongly reduced photoluminescence due to the enhanced charge separation thus improving the catalyst efficiency under visible light irradiation. The material with 1.6 wt% of barbituric acid showed the best photocatalytic performance and electrochemical properties. This photocatalyst was selected for immobilisation on a conductive carbon foam, which promotes a higher electrochemical active surface area and enhanced mass transfer. This three-dimensional metal-free electrode was employed for the photoelectrochemical inactivation of two different microorganisms, Escherichia coli, and Enterococcus faecalis, obtaining removals below the detection limit after 30 min in simulated faecal-contaminated waters. This photoelectrochemical reactor was also applied to treat polluted river and urban waste waters, and the faecal contamination indicators were vastly reduced to values below the detection limit in 60 min in both cases, showing the wide applicability of this innovative photoelectrode for different types of polluted aqueous matrices.

Advances on Graphyne-Family Members for Superior Photocatalytic Behavior.

Graphyne (GY) and graphdiyne (GDY) have been employed in photocatalysis since 2012, presenting intriguing electronic and optical properties, such as high electron mobility and intrinsic bandgap due to their high π-conjugated structures. Authors are reporting the enhanced photocatalytic efficiency of these carbon allotropes when combined with different metal oxides or other carbon materials. However, the synthesis of graphyne-family members (GFMs) is still very recent, and not much is known about the true potential of these photocatalytic materials. In this review article, the implications of different synthesis routes on the structural features and photocatalytic properties of these materials are elucidated. The application of GFMs in the nicotinamide adenine dinucleotide (NADH) regeneration, hydrogen and oxygen evolution, and carbon dioxide reduction is discussed, as well as in the degradation of pollutants and bacteria inactivation in water and wastewater treatment.