Hybrid Reduced Graphene Oxide/GaN Nanocolumns on Flexible Niobium Foils for Efficient Photoelectrochemical Water Splitting

Abstract

We present the photoelectrochemical (PEC) watersplitting properties of pristine and reduced graphene oxide (rGO)coated GaN nanocolumns (NCs) on flexible niobium (Nb) metal foils. The structural, optical, and electronic structure analyses of rGOcoated GaN-NCs on Nb foils revealed the formation of a rGO/GaN-NCs hybrid structure. Further, the valence-band studies of pure GaN-NCs shows valence-band maxima at ∼3.0 eV below the Fermi level, which decreased to ∼2.8 eV for rGO/GaN-NCs. The PEC measurement performed on pristine GaN-NCs under standard (1 Sun) conditions shows an effective photocatalytic nature with a photocurrent density of ∼60 μA/cm 2 at 0.8 V (vs Ag/AgCl) in a 1 M oxalic acid electrolyte, which increases to ∼110 μA/cm 2 for rGO/ GaN-NCs. The efficient PEC characteristics of rGO/GaN-NCs are attributed to the effective charge separation/transport of photogenerated carriers. Furthermore, transient photocurrent measurement reveals that hybrid and pristine GaN-NCs on flexible metal foil have a fast and stable photoresponse in an aqueous solution. The development of a hybrid nitride nanostructure-based PEC device on flexible metal foils paves the way toward developing scalable PEC devices for hydrogen production applications.

Heterojunction Bi2Se3/Sb2Se3 on Flexible Mo Metal Foils for Photoelectrochemical Water Splitting Applications

“…The photo-switching behavior of the photoelectrodes was investigated by calculating the rise and decay time, and these are found as follows: fall/rise time: 7.1/7.2 s for Bi 2 Se 3 /Mo and 4.02/3.95 s for Sb 2 Se 3 /Mo, while the improved photocurrent response with fall/rise time: 3.2/3.07 s for the Bi 2 Se 3 /Sb 2 Se 3 heterojunction (Figure S2). As the Bi 2 Se 3 , Sb 2 Se 3 , and Bi 2 Se 3 /Sb 2 Se 3 structures were grown on a polycrystalline metal foil, any leakage current due to microstructure defects at the film–metal substrate interface, pinholes, or non-uniformity of the film might lead to the non-zero dark current in the photo-switching behavior . Further to understand the charge-transfer kinetics between the photoelectrode and electrolyte interface, an EIS measurement was performed (at an AC voltage of 0.01 V under light irradiation).…”

“…As the Bi 2 Se 3 , Sb 2 Se 3 , and Bi 2 Se 3 / Sb 2 Se 3 structures were grown on a polycrystalline metal foil, any leakage current due to microstructure defects at the film−metal substrate interface, pinholes, or non-uniformity of the film might lead to the non-zero dark current in the photo-switching behavior. 44 Further to understand the charge-transfer kinetics between the photoelectrode and electrolyte interface, an EIS measurement was performed (at an AC voltage of 0.01 V under light irradiation). The Nyquist plot with the corresponding equivalent circuit diagram is shown in Figure 8d.…”

“…In addition, there is a natural provision for back contact, when the metal substrate is used . Some recent reports offer a fundamental understanding of flexible photoelectrodes which can be used to develop heterojunction solar-based devices for the generation of solar fuels. − …”

Metal Phthalocyanine Sensitized Photoelectrochemical Cell Assembling with Azide‐Functionalized Reduced Graphene and Quaternary Metal Chalcogenide Composites

“…al. [16] Briefly, 40 mg of sodium azide was added into a dispersion of graphene oxide (GO) in 50 ml of water (1 mg/ml). The resulting mixture was agitated at 10 °C for one hour.…”

MoS2 thin film decorated TiO2 nanotube arrays on flexible Ti foil for solar water splitting application

“…The use of flexible substrates may enable large-scale rollto-roll PEC devices [37,38]. Some reports on flexible photoelectrode offer a fundamental understanding of developing next-generation roll-to-roll energy device fabrication [38][39][40]. In this work, we have deposited MoS 2 thin film using the CVD technique on TiO 2 nanotube on flexible thin Ti foil.…”