Assessment of divergent functional properties of seed-like strontium molybdate for the photocatalysis and electrocatalysis of the postharvest scald inhibitor diphenylamine

•Two phenomena of SrMoO4 are examined: photon absorption and electrochemical behavior.•The photon absorption ability of SrMoO4 mostly generates OH radicals for the degradation of DPAH.•The major contribution of the reaction is generation of radical cations (DPAH+).•The detection range of DPAH is 0.1-35 µM with a low detection limit of 30 nM.•A challenge of this study is selectivity, because DPAH+ is highly active to both anions/cations.

The bifunctional activity of strontium molybdate (SrMoO4) in the photodegradation and electrocatalytic determination of diphenylamine (DPAH) was identified and demonstrated. The photocatalytic and electrocatalytic activity of SrMoO4 were influenced by its structural properties. Those structural properties are scrutinized by various physical spectroscopic and microscopic tools. In this work, we mainly concentrated on two phenomena of SrMoO4, the photon absorption and electrochemical behavior. UV-visible spectroscopy was used to assess the photon absorption characteristics of SrMoO4, which mostly generates OH radicals for the degradation of DPAH. The rate of photodegradation was demonstrated in terms of irradiation time, pH, catalyst loading, and initial concentration. On the other hand, voltammetry was used to evaluate the electrochemical behavior of SrMoO4. The overall reaction pathways of DPAH showed that the major contribution of the reaction is generation of radical cations (DPAH+). Therefore, we can determine the concentration of DPAH by measuring DPAH+. Differential pulse voltammetry is a suitable analytical tool to measure DPAH+, which determined the DPAH in the linear range 0.1-35 µM and with a lowest detection limit of 30 nM. One of the greatest challenges of this determination is the selectivity, because DPAH+ is highly reactive toward similar functionalities such as anions and cations. Therefore, we carefully investigated and discussed the selectivity in the presence of interfering compounds.

Graphical abstractPhotocatalytic degradation of diphenylamine on strontium molybdate: the four possible reaction pathways.Download high-res image (48KB)Download full-size image