Vincenzo Balzani

Stiamo viaggiando nell’infinità dell'Universo sul pianeta Terra, un'astronave con 7,8 miliardi di passeggeri che non potrà mai "atterrare" da nessuna parte e neppure fermarsi in qualche luogo per caricare risorse o scaricare rifiuti. Le risorse su cui noi passeggeri possiamo contare sono i materiali che compongono l'astronave e la luce del sole. Qualsiasi danno all’astronave deve essere riparato e qualsiasi problema deve essere risolto da noi passeggeri. Gli scienziati avvertono da molti anni che non stiamo custodendo il pianeta e i sociologi ammoniscono che le enormi disparità economiche e sociali stanno diventando insostenibili. Da alcuni mesi, un virus pericoloso e altamente contagioso, Covid-19, sta circolando sull'astronave Terra. Dovremmo prenderlo come un avvertimento da parte della Natura per avviarci verso la sostenibilità ecologica e sociale.

The photocatalytic mechanism reported in a recent Communication to produce the radical anion of pyrenes postulates a highly endergonic electron transfer process. An analysis of the thermodynamics is reported together with the proposal of an alternative thermodynamically feasible mechanism.

The energy transition from fossil fuels to renewables is already ongoing, but it will be a long and difficult process because the energy system is a gigantic and complex machine. Key renewable energy production data show the remarkable growth of solar electricity technologies and indicate that crystalline silicon photovoltaics (PV) and wind turbines are the workhorses of the first wave of renewable energy deployment on the TW scale around the globe. The other PV alternatives (e.g., copper/indium/gallium/selenide (CIGS) or CdTe), along with other less mature options, are critically analyzed. As far as fuels are concerned, the situation is significantly more complex because making chemicals with sunshine is far more complicated than generating electric current. The prime solar artificial fuel is molecular hydrogen, which is characterized by an excellent combination of chemical and physical properties. The routes to make it from solar energy (photoelectrochemical cells (PEC), dye‐sensitized photoelectrochemical cells (DSPEC), PV electrolyzers) and then synthetic liquid fuels are presented, with discussion on economic aspects. The interconversion between electricity and hydrogen, two energy carriers directly produced by sunlight, will be a key tool to distribute renewable energies with the highest flexibility. The discussion takes into account two concepts that are often overlooked: the energy return on investment (EROI) and the limited availability of natural resources—particularly minerals—which are needed to manufacture energy converters and storage devices on a multi‐TW scale.

See the light of day: Light is the fastest way of transferring energy and information through space, and in chemistry it can perform the dual role of reactant and product. Sunlight, a really unique reactant, represents our ultimate energy source. Chemists are engaged in designing systems for the conversion of light into electrical or chemical energy and vice versa to create a more sustainable way of life.

Complexity is a common feature of all problems facing mankind and in such a complex world we need science to propose solutions. Science, indeed, is growing in all directions and permeates more and more the human society. As pointed out by several scientists, however, the development of science increases the fragility of our world. A democratic society must discuss the role of science and must collectively take decisions on the development of science. Scientists should be concerned about the world in which we live and the society that we are going to construct. They should discuss the relationship between science and society with students, explain science to laymen, and educate politicians on the most important scientific issues, thereby playing an important role as authoritative, informed, and concerned citizens of the planet Earth.