Photocatalytic Production of Oxygen by Nitrogen Doped Graphene Oxide Nanospheres: Synthesized via Bottom‐Up Approach Using Dibenzopyrrole

Abstract

AbstractIn this article, we present the formation of nitrogen (N) doped graphene oxide nanospheres (N‐GONs) and investigate their applicability for photocatalytic water splitting. We chose a simple “bottom‐up” method for synthesizing N‐GONs. Dibenzopyrrole as a basic structural unit was used for constructing N‐GONs. Nitration is an intermediate step, subsequent hydrothermal treatment of nitro derivatives imparted oxygen functionalities, which was well proved via CHNS and XPS analysis. ∼14 % and 39 % of nitrogen and oxygen were present inside N‐GONs. The average size of N‐GONs is in‐between 30–80 nm. N‐GONs typically have a band gap of nearly 2.61 eV. The valance and the conduction bands alignments of N‐GONs w.r.t to standard hydrogen electrode were evaluated through UPS and XPS studies. The alignments were found to be well suited for H2O splitting applications. N‐GONs have n‐type semiconductor features and a charge carrier density of 1.12×1022 cm−3. While studying photocatalytic dissociation of water we identified oxygen as the only product. Significantly, 1 g of N‐GONs produced ∼1.3 mmol of oxygen over the course of 1 h. These backgrounds clearly suggest the possibilities of ongoing oxygen reduction and oxygen evolution reactions simultaneously. No‐significant traces of H2O2 were observed which suggested immediate H2O2 disproportionation to O2 and H2O on N‐GONs. The proposed photocatalytic activity of N‐GONs is also confirmed by RRDE method for ORR catalysis.