Simultaneous p-nitrophenol remediation and hydrogen generation via dual-function photoelectrolytic cell: P–TiO2 photoanode and CuP cathode

Abstract

In the context of electrochemical cells capable of oxidizing organic matter with the concomitant formation of H2, this report explores the use of P–TiO2 and TiO2 photoanodes paired with CuP cathodes in photoelectrolytic cells. Electrochemical assistance to photocatalysis was required to achieve p-nitrophenol (PNP) oxidation without accumulation of intermediates, while the charge balance is completed with the production of H2 at the cathode. In relation to P–TiO2 and TiO2 photoanodes, the inverse balance between electron transfer and recombination has been demonstrated by photocurrent and photoluminescence measurements. The incorporation of P in TiO2 (P/Ti ratio 1 %) favors photocatalysis by reducing recombination processes: P–TiO2 defines a higher photocurrent and lower photoluminescence than TiO2, in addition to photocatalytically oxidizing p-nitrophenol more quickly. In relation to CuP cathodes, the Tafel analysis shows that the performance of different CuP cathodes in the production of H2 is superior to that of Cu, which in turn depends on the conditions established in the electrocrystallization. In the operation of the photoelectrolytic cell, it has been observed that the production of H2 using the CuP cathode with a P/Cu ratio of 5 % is higher. Furthermore, better cell performance has been achieved by using P–TiO2 instead of TiO2 as the photoanode. These results highlight the importance of optimizing electrochemical conditions to improve efficiency and yield in hydrogen production by photoelectrolysis.