In this paper we present an easy, quick and scalable route, based on anodic oxidation, for the preparation of mesoporous SnO₂ as an efficient electrocatalyst for the CO₂ reduction reaction (CO₂RR). Crystallographically interconnected SnO₂ nanocrystals with abundant grain boundaries, high specific surface area and easily accessible porosity result to be active and selective for the CO₂RR. This electrocatalyst shows faradaic efficiency (FE) of about 95% at -0.97 V and -1.06 V vs. reversible hydrogen electrode (RHE) towards the formation of predominant HCOOH and minor CO. A peak FE value of 82 % for the HCOOH production is obtained at -1.06 V vs. RHE. High HCOOH partial current densities of 10.2 mA cm^-2 and 15.3 mA cm^-2 are observed at -0.97 V and -1.15 V vs. RHE, respectively. Thorough electrochemical characterizations demonstrate that the synthesized SnO₂-based gas diffusion electrode allows efficient diffusion of CO₂ even at high kinetics, due to the highly open porous structure. The good understanding of the catalyst behavior is achieved also after the electrode testing and it shows that the proposed preparation route results in a stable and durable material. The here reported promising results can be exploited for developing high-performance and sustainable electrocatalysts with a high potentiality to be implemented in real CO₂ conversion devices.

The conversion of carbon dioxide into value-added products using sunlight, also called artificial photosynthesis, represents a remarkable and sustainable approach to store solar energy, transforming it into chemical energy. There are mainly two strategies to carry out this process: the photocatalytic reduction of carbon dioxide (CO2) or the photovoltaic-powered electrochemical reduction of CO2. Herein we focus on the latter route, i.e. the development of a device coupling a solar cell to an electrochemical reactor for CO2 reduction. Different literature works demonstrated the possibility to achieve such a coupling but no evidence of a real integration between the two systems has been given up-to-now. In this work we present an integrated device constituted by a dye-sensitized solar module (based on a mesoporous titanium dioxide photoanode) and an electrochemical cell (based on copper-tin cathode). The integration of the two systems is accomplished through a common platinum-based electrode, which acts either as cathode for the photovoltaic module and as anode for the electrochemical reactor. The integrated system was characterized by a stable current of 3.6 mA under continuous solar irradiation, enabling the production of 80 mmol of carbon monoxide per day, with a solar-to-fuel efficiency equal to 0.97%.

High-energy, long gamma-ray bursts (GRBs) can be generated by the core collapse of massive stars at the end of their lives. When they happen in the close-by universe they can be exceptionally bright, as seen from the Earth in the case of the recent, giant, long-lasting GRB221009A. GRB221009A was produced by a collapsing star with a redshift of 0.152: this event was observed by many gamma-ray space experiments, which also detected an extraordinary long gamma-ray afterglow. The exceptionally large fluence of the prompt emission of about 0.013 erg cm⁻² illuminated a large geographical region centered on India and including Europe and Asia. We report in this paper the observation of sudden electron flux changes correlated with GRB221009A and measured by the HEPP-L charged particle detector on board the China Seismo-Electromagnetic Satellite, which was orbiting over Europe at the time of the GRB event. The time structure of the observed electron flux closely matches the very distinctive time dependence of the photon flux associated with the main part of the emission at around 13:20 UTC on 2022 October 9. To test the origin of these signals, we set up a simplified simulation of one HEPP-L subdetector: the results of this analysis suggest that the signals observed are mostly due to electrons created within the aluminum collimator surrounding the silicon detector, providing real-time monitoring of the very intense photon fluxes. We discuss the implications of this observation for existing and forthcoming particle detectors on low Earth orbits.

Time-dependent energy spectra of galactic cosmic rays (GCRs) carry crucial information regarding their origin and propagation throughout the interstellar environment. When observed at the Earth, after traversing the interplanetary medium, such spectra are heavily affected by the solar wind and the embedded solar magnetic field permeating the inner sectors of the heliosphere. The activity of the Sun changes significantly over an 11 yr solar cycle—and so does the effect on cosmic particles; this translates into a phenomenon called solar modulation. Moreover, GCR spectra during different epochs of solar activity provide invaluable information for a complete understanding of the plethora of mechanisms taking place in various layers of the Sun’s atmosphere and how they evolve over time. The High-Energy Particle Detector (HEPD-01) has been continuously collecting data since 2018 August, during the quiet phase between solar cycles 24 and 25; the activity of the Sun is slowly but steadily rising and is expected to peak around 2025/2026. In this paper, we present the first spectra for ∼50–250 MeV galactic protons measured by the HEPD-01 instrument—placed on board the CSES-01 satellite—from 2018 August to 2022 March over a one-Carrington-rotation time basis. Such data are compared to the ones from other spaceborne experiments, present (e.g., EPHIN, Parker Solar Probe) and past (PAMELA), and to a state-of-the-art three-dimensional model describing the GCRs propagation through the heliosphere.