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

Abstract

In 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 H 2 O splitting applications. N-GONs have n-type semiconductor features and a charge carrier density of 1.12 × 10 22 cm À 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 H 2 O 2 were observed which suggested immediate H 2 O 2 disproportionation to O 2 and H 2 O on N-GONs. The proposed photocatalytic activity of N-GONs is also confirmed by RRDE method for ORR catalysis.

Visible Light-Promoted Enhanced Photocatalytic Hydrogen Generation by the CeF3:Ho3+-Incorporated TiO2 Nanosystem

“…Typically, the rate is the highest at the beginning and gradually lowers and becomes negligible with time. In the case of photocatalytic activity, such patterns have frequently been observed. − This is primarily due to the production and subsequent adsorption of oxidative species (H 2 O 2 , HCHO, CO 2 , etc.) on the photocatalyst’s surface over the course of time. , After a few hours of repose, the catalyst was discovered to be active once again (Figure S2, Supporting Information).…”