Abstract
An “indirect” photo-electrochemical sensor is presented for the measurement of a mixture of analytes including reducing sugars (e.g. glucose, fructose) and non-reducing sugars (e.g. sucrose, trehalose). Its innovation relies on the use of a palladium film creating a two-compartment cell to separate the electrochemical and the photocatalytic processes. In this original way, the electrochemical detection is separated from the potential complex matrix of the analyte (i.e. colloids, salts, additives, etc.). Hydrogen is generated in the photocatalytic compartment by a Pt@g-C3N4 photocatalyst embedded into a hydrogen capture material composed of a polymer of intrinsic microporosity (PIM-1). The immobilised photocatalyst is deposited onto a thin palladium membrane, which allows rapid pure hydrogen diffusion, which is then monitored by chronopotentiometry (zero current) response in the electrochemical compartment. The concept is demonstrated herein for the analysis of sugar content in commercial soft drinks. There is no requirement for the analyte to be conducting with electrolyte or buffered. In this way, samples (biological or not) can be simply monitored by their exposition to blue LED light, opening the door to additional energy conversion and waste-to-energy applications.
Highlights
LC-MS analyses were performed using an Agilent QTOF 6545 with Jetstream ESI spray source coupled to an Agilent 1260 Infinity II Quat pump HPLC with 1260 autosampler, column oven compartment and variable wavelength detector (VWD)
It has been shown that a palladium film can be employed to separate an analyte compartment with glucose and an electrochemical compartment filled with aqueous 10 mM HCl
Production of hydrogen in the analyte compartment driven by a blue LED (385 nm) and catalysed by a Pt@g-C3N4 photocatalyst deposit causes the equilibrium potential of the palladium working electrode to respond
Summary
A palladium film membrane cell is employed to separate the electrochemical compartment (see Schematic 1) from the photo-catalysis compartment. PIMs have been developed a decade ago [16] as a novel class of glassy (molecularly rigid) porous materials with excellent processability These materials have emerged as useful components in electrochemical processes [17] due to the ability to stabilise surfaces, immobilise catalysts [18], and to capture gases such as hydrogen under ‘‘triphasic” conditions in the presence of aqueous electrolytes [19].
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