Hybrid Organic/Inorganic Nanostructures for Highly Sensitive Photoelectrochemical Detection of Dissolved Oxygen in Aqueous Media

Abstract

Precise, reliable, and remote measurement of dissolved oxygen in aqueous media is of great importance for many industrial, environmental, and biological applications. In particular, photoelectrochemical sensors working in differential mode have recently demonstrated promising properties, in terms of stability, sensitivity, and application potential. Here, a new approach is presented, combining visible light sensitivity, effi cient photocurrent generation, and solution-processed fabrication methods of conjugated polymers, with charge carriers selectivity, energetic alignment favorable to effi cient interfacial charge transfer and high surface area achievable by using metal oxide nanostructures. Extensive characterization and optimization of the hybrid organic/inorganic system are carried out, leading to the realization of an oxygen sensor device, based on nanostructured palladium oxide/poly[(9,9-dioctylfl uorenyl-2,7-diyl)-alt -5,5-(4′,7′-di-2thienyl-2′,1′,3′-benzothiadiazole]/[6,6]phenyl-C61-butyric acid methyl ester (PdO/APFO-3:PCBM) as materials of choice. State-of-the-art sensitivity, amounting at −5.87 µA cm −2 ppm −1 , low background signal, in the order of −4.85 µA cm −2 , good electrochemical stability for more than 2 h of continuous functioning and high reproducibility of the signal over the pH 1 to 10 range, are reported, making the hybrid device suitable for several practical uses. The results fully validate the mixed organic/inorganic approach for photoelectrochemical applications, and pave the way for its further exploitation in fi elds like waste water treatment, environmental monitoring, and water splitting.

Photocatalytic Activity of Polymer Nanoparticles Modulates Intracellular Calcium Dynamics and Reactive Oxygen Species in HEK-293 Cells

“…The photo-electrochemical activity of P3HT polymer thin films in an aqueous saline environment has been reported in a number of recent works (Lanzarini et al, 2012; Bellani et al, 2015; Giron et al, 2016; Tullii et al, 2017). The observed photocurrent generation has been attributed to photo-electrochemical reactions, leading to oxygen and, less efficiently, to hydrogen reduction.…”

Graphene-Based Hole-Selective Layers for High-Efficiency, Solution-Processed, Large-Area, Flexible, Hydrogen-Evolving Organic Photocathodes

“…The FoM of the photocathodes are J 0V vs RHE = -2.16 mA cm -2 , V o = 0.56 V vs. RHE, Φ saved,NPA,C = 0.29%, Φ saved,ideal = 0.21% for GO and J 0V vs RHE = -1.33 mA cm -2 , V o = 0.50 V vs. RHE, Φ saved,NPA,C = 0.18%, Φ saved,ideal = 0.15% for RGO. The better performances obtained by using GO with respect those recorded by using RGO are linked with the E F of GO matching (~-4.9 eV) with the HOMO P3HT (~-5 eV), 95,96 while the E F of RGO (~-4.4 eV) could lead to a rectifying (i.e., Schottky barrier) 177 FTO/rr-P3HT contact for the hole extraction. 165 Furthermore, the inhomogeneity of the RGO layer, evidenced by SEM analysis, Figures S4d, also affects the quality of the RGO/rr-P3HT junctions, determining charge recombination pathways (i.e., leakage currents) in presence of blend-uncovered flake aggregates.…”

Solution‐Processed GaSe Nanoflake‐Based Films for Photoelectrochemical Water Splitting and Photoelectrochemical‐Type Photodetectors

“…The validation of the GaSe nanoflakes for photoelectrochemical (PEC) reactions could pave the way toward the design of novel GaSe‐based PEC‐type photodetectors/PEC sensors that can operate with low voltage sources, or even without external energy supply systems, as well as eliminate complex device manufacturing. Notably, by detecting an analyte via photoinduced electrochemical reactions, PEC sensors offer several advantages over electrochemical sensor, since they can operate in differential mode to reduce the background signal (down to the limit of lock‐in detection noise) and avoid frequent recalibrations . Therefore, the validation of GaSe and other group‐III monochalcogenides as novel photoelectrochemically active 2D materials represents a great potential for the design of efficient photocatalysts and innovative optoelectronic devices .…”

“…[42,55,56] Meanwhile, the distance between the photogenerated charges and the surface area is virtually reduced to zero, [42,55,56] suppressing electron-hole recombination losses. [57] The validation of the GaSe nanoflakes for photoelectrochemical (PEC) reactions could pave the way toward the design of novel GaSe-based PEC-type photodetectors/PEC sensors that can operate with low voltage sources, or even without external energy supply systems, [50,[58][59][60] as well as eliminate complex device manufacturing. Notably, by detecting an analyte via photoinduced electrochemical reactions, PEC sensors offer several advantages over electrochemical sensor, since they can operate in differential mode to reduce the background signal (down to the limit of lock-in detection noise) [60,61] and avoid frequent recalibrations.…”

“…Notably, by detecting an analyte via photoinduced electrochemical reactions, PEC sensors offer several advantages over electrochemical sensor, since they can operate in differential mode to reduce the background signal (down to the limit of lock-in detection noise) [60,61] and avoid frequent recalibrations. [60,[62][63][64] Therefore, the validation of GaSe and other group-III monochalcogenides as novel photoelectrochemically active 2D materials represents a great potential for the design of efficient photocatalysts and innovative optoelectronic devices. [65][66][67][68][69] Despite these encouraging driving factors, the PEC properties of GaSe are still experimentally uncharted.…”