Introduction by guest editors

This issue of Photochemical & Photobiological Sciences contains a selection of papers presented at the 9^th European Meeting on Solar Chemistry & Photocatalysis: Environmental Applications – SPEA 9, held at the convention center in Strasbourg, France, between 13^th and 17^th of June, 2016.

This meeting was organized by the Institut de chimie et procédés pour l’énergie, l'environnement et la santé (ICPEES) – Institute of chemistry and processes for energy, environment and health, under the auspices of the French national center for scientific research (CNRS) and the University of Strasbourg. In line with the history of previous meetings of the biennial European SPEA series, the event intended to create a lively and convivial sharing platform for participants from academia, research centers, small and medium enterprises, industry and government decision makers, working in the field of photocatalysis and solar photochemistry applied to environmental reactions, sustainable chemistry and energy, to gather and disseminate both experience and knowledge, and pave the way for future research and actual challenges to be faced.

The SPEA 9 thematics addressed major societal concerns, and were more specifically devoted to environmental applications and public health by focusing on novel materials, products and processes for remediation or ones with green chemistry aspects, as well as solar renewable carbon-neutral energy with the production of clean hydrogen, CO₂ valorization or solar fuel aspects.

The conference attracted over 350 participants including 6 world-renowned invited speakers who delivered stimulating plenary lectures, 4 extended keynote speakers and 140 doctoral students. Although over 70% of the participants came from Europe, SPEA 9 has broken geographical borders and gathered people from 47 nationalities from all around the world, including the Americas (14%), Asia (10%), Oceania and Africa. Beside the plenary and keynote lectures, the scientific program contained 58 regular oral talks, 318 poster contributions were discussed during the whole congress, and the work of 30 doctoral students was highlighted within 3 flash oral talk sessions. The scientific program was organized into thematic plenary sessions focused on (i) water treatment and advanced oxidation processes; (ii) visible light photocatalysis; (iii) improving photocatalytic processes; (iv) photocatalytic surfaces and membranes; (v) photocatalysis for hydrogen production; (vi) photocatalysis for synthesis reactions; (vii) photocatalytic CO₂ conversion and solar fuels; (viii) water splitting and hydrogen production; (ix) fundamentals and characterization of photocatalysts; and (x) photocatalysis and life science.

The present collection includes articles dealing with new semiconductor photocatalysts, wastewater treatment, photoassisted inactivation of pathogens, water splitting by photoelectrochemical processes, CO₂ photoreduction and new UV LED photoreactors. Although not exhaustive, the selection reflects excellent perspectives for application of the processes described. The next paragraph briefly summarizes and highlights these contributions.

Homogeneous and heterogeneous photocatalytic degradation and mineralization of pharmaceuticals and other emerging pollutants, including humic-like substances as auxiliaries for photo-Fenton treatment were studied. In the area of semiconductor modification, there are contributions focusing on tungstophosphoric acid, TiO₂ sensitized by Ru(II) polyaze complexes or Ce-doped ZnO for enhancing visible light absorption. New photosensitive composites based on materials free of TiO₂ were also proposed, including magnetic nanoparticles. The utilization of UV-A radiation LEDs in photoreactors was proposed for methylene blue degradation and a photo-Fenton process for micropollutant removal. The theme of photocatalytic transformation for energy production through reduction was addressed by a solid-state photoelectrochemical cell with TiO₂ nanotubes for water splitting. Anoxic processes were also applied to CO₂ reduction over photocatalysts. Water disinfection was considered using silver functionalized titanate nanotubes.

The invited editors wish to express their appreciation to all the authors for their contributions to this special issue and thank the editorial staff of Photochemical and Photobiological Sciences for assistance. Sixto Malato wishes to thank the Spanish Ministry of Economy and Competitiveness financial support under the TRICERATOPS Project (Reference: CTQ2015-69832-C4-1-R).

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