Development of Cobalt Oxide-Decorated Reduced Graphene Oxide-Supported Nickel Alloy Coating for Efficient Photocatalytic Hydrogen Generation

Abstract

Being a narrow band gap semiconductor, the photocatalytic activity of bare Ni 2 P is highly limited. However, a proper band gap tuning of Ni 2 P through effective composite formation furnishes a fruitful strategy for developing active photocatalytic materials. In this regard, the present work reports the application of an efficient photocatalytic ternary composite in the form of a coating formed from CoO/rGO and Ni 2 P. The simultaneous reduction of GO to rGO disperses crystalline CoO nanoparticles in it. The CoO-embedded rGO nanosheet can act as an efficient conducting material that helps to mediate the redox reactions in CoO and Ni 2 P. CoO/rGO enriches the catalytically active sites in the Ni 2 P surface with an improvement in the surface topography. Moreover, the possibilities of interactions such as hydrogen bonding among the oxygen functional groups in CoO/rGO, with phosphorus in Ni 2 P, lead to an intimate contact among them for the fast electronic movement for proton reduction. Consequently, the CoO/rGO-Ni 2 P composite coating displays a benchmark performance for solar-driven hydrogen generation and produces 4.98 mmol/g hydrogen for 1 h irradiation after a successful compositional tuning. The long-lasting activity and excellent stability of the composite coating, even after 15 cycles, are attributed to the additional role of Ni 2 P as a catalyst support bed for CoO/rGO which can impart stability to the entire catalyst system.

Yeast Reduced Ti3+ Self-Doped SrTiO3/rGO-In-Ni2P Nanocomposite for Efficient Visible Light-Driven Hydrogen Generation

“…The peak assigned with SrTiO 3 /yrGO shows comparatively similar result with pure SrTiO 3 and SrTiO 3 /rGO. Figure E shows the N 1s high resolution spectra which is deconvoluted into characterization peaks at 399.2 and 400.4 eV showing pyridinic N and pyrrolic N, respectively, possibly from the NADPH biofuctionalization acquired from the yeast-induced reduction. , In Figure F, the binding energies at 856.0 and 874.2 eV accompanied by two shakeup satellite peaks signifies the presence of Ni 2+ , likely to be resulting from superficial oxidation due to air contact . The binding energies of 852.8 and 870.4 eV correspond to Ni 2p 3/2 and Ni 2p 1/2 states, respectively, within Ni 2 P. Further exploration of the P 2p spectra (Figure G) reveals two prominent peaks at 129.3 and 130.2 eV, corresponding to P 2p 1/2 and P 2p 3/2 states originating from Ni 2 P .…”

“…35,42 In Figure 2F, the binding energies at 856.0 and 874.2 eV accompanied by two shakeup satellite peaks signifies the presence of Ni 2+ , likely to be resulting from superficial oxidation due to air contact. 43 The binding energies of 852.8 and 870.4 eV correspond to Ni 2p 3/2 and Ni 2p 1/2 states, respectively, within Ni 2 P. Further exploration of the P 2p spectra (Figure 2G) reveals two prominent peaks at 129.3 and 130.2 eV, corresponding to P 2p 1/2 and P 2p 3/2 states originating from Ni 2 P. 44 The appearance of peaks at approximately 135.0 and 133.8 eV are due to both the generation of phosphate species by atmospheric air exposure, 45 as well as the involvement of the phosphate group in NADPH functionalization.…”

“…Figure S7C shows the absorption peak of bare Ni 2 P. Band gap of the bare Ni 2 P are calculated using Tauc plot (Figure S7F) is 1 eV agreed with the previous research work. 43 The decoration of the SrTiO 3 /yrGO on to the Ni 2 P matrix leads to the alignment of the wide band gap by the interaction of Ni 2 P. The Ni 2 P anchoring leads to a straddling interaction of the band gap of SrTiO 3 and Ni 2 P by the support of rGO leads to a heterojunction. Electrons from the valence band SrTiO 3 goes to the conduction band of SrTiO 3 on light irradiation which further transferred to the conduction band of Ni 2 P through the electron conducting rGO sheet.…”