The development of high-performing sensing materials, able to detect ppb-trace concentrations of volatile organic compounds at low temperatures, is required for the development of next-generation miniaturized wireless sensors. Here, we present the engineering of selective room-temperature chemical sensors, comprising of highly porous tin dioxide (SnO2) – graphene ox-ide (GO) nano-heterojunction layouts. The optoelectronic and chemical properties of these highly porous (> 90%) p-n hetero-junctions were systematically investigated in terms of composition and morphologies. Optimized SnO2-GO layouts demon-strate significant potential as both visible-blind photodetectors and as selective room-temperature chemical sensors. Notably, a low GO content results in an excellent UV light responsivity (400 A W-1), with short rise and decay times, and room-temperature high chemical sensitivity with selective detection of volatile organic compounds such as ethanol down to 100 ppb. In contrast, a high concentration of GO drastically decreases the room-temperature response to ethanol, and results in good selectivity to ethylbenzene. The feasibility of tuning the chemical selectivity of the sensor response by engineering the relative amount of GO and SnO2 is a promising feature that may guide the future development of miniaturized solid-state gas sensors. Furthermore, the excellent optoelectronic properties of these SnO2-GO nano-heterojunctions may find applications to various other areas such as optoelectronic devices and (photo)electrocatalysis.

Pharmaceutics and personal care products (PPCPs) are raising growing concern due to their widespread usage and resistance to conventional remediation techniques. Several of them raise significant health and environmental concerns, especially when present in complex mixtures. Due to their chemical resistance, Advanced Oxidation Processes (AOPs) are needed for their complete removal from surface and wastewaters. In the present work, photocatalysis by titanium dioxide (TiO₂) under UV and simulated solar irradiation was adopted to degrade tetracycline hydrochloride, paracetamol, caffeine and atenolol, both as single pollutants and in mixtures. All molecules showed high removal and mineralization degrees. Moreover, no interference effects decreased the efficiency of the processes in the case of pollutant mixtures, achieving 60% of mineralization after 6 h. An immobilized TiO₂ system was also developed by depositing titania on titanium meshes. A 50% mineralization degree of the pollutant mixture was obtained after 6 h, revealing a suitable efficiency for field applications. Eventually, the impact of the matrix composition on the photocatalytic efficiency was investigated by studying the reaction both in simulated drinking water and in commercial bottled mineral water. The scavenger role played by HCO₃ ⁻ species appears to be dominant in inhibiting the mineralization.

Fouling and passivation are the major drawbacks for a wide applicability of electroanalytical sensors based on nanomaterials, especially in biomedical and environmental fields. The production of highly engineered devices, designed ad hoc for specific applications, is the key factor in the direction of overcoming the problem and accessing effective sensors. Here, the fine-tuning of the system, composed of a highly ordered distribution of silver nanoparticles between a bottom silica and a top titania layer, confers multifunctional properties to the device for a biomedical complex challenge: dopamine detection. The crucial importance of each component towards a robust and efficient electroanalytical system is studied. The total recovery of the electrode performance after a simple UV-A cleaning step (self-cleaning), due to the photoactive interface and the aging resistance, is deeply investigated.