Reduced graphene oxide modified CuBi₂O₄ as an efficient and noble metal free photocathode for superior photoelectrochemical hydrogen production

Abstract

Favourable charge recombination kinetics are achieved to enhance solar hydrogen production utilizing reduced graphene oxide coated onto noble metal free CuBi2O4.

Challenges and prospects about the graphene role in the design of photoelectrodes for sunlight-driven water splitting

“…As stated in the last section, graphene can modify different material properties depending on the deposition technique and the chosen derivative, but how this insertion affects the photocathode electronic structure? Some studies 12,[116][117][118] have shown by XPS and Raman that the graphene or rGO addition into Cu based photocathodes allow the formation of Cu-O-C bonds, indicating a superior interaction and interfacial charge transfer between graphene and Cu compounds which reduce the electron density around the Cu material. It is worth mentioning that in these cases, graphene-based materials have been synthesized separately and subsequently added into the electrode by methods such as spin coating, drop casting or impregnation.…”

“…Absorption measurements of photocathodes modied by graphene, 116 rGO, 117 and NGQDs 120 indicated that this modication increases the absorption range of the nanocomposites in the visible region but, in all circumstances, the band gap analysis showed that graphene based materials have not been incorporated into the lattice. However, in cases when a higher concentration of graphene (or its derivatives) is added, a competition of light absorption between graphene and the semiconductor and light blocking effects 12,116,121,122 are noticeable.…”

“…Although the chronoamperometric measurements have been performed at 0 V vs. RHE, the longest test data reported is 20 minutes which suggest the electrode photostability is not enough for scale-up. Even if several authors affirm that graphene electron mobility and its behaviour as electron acceptor boost the transfer of photogenerated electrons from photocathode to the electrolyte, 12,116,121 it must be taken into account that Cu based materials by themselves can achieve remarkable performance during limited time and, for this reason, it is necessary to focus on resolve their stability drawbacks to then create strategies focused on charge transfer kinetics. Despite all mentioned above provides valuable information to create new strategies for photocathode design, some issues are still elusive.…”

“…It has been proved that the coupling between a semiconductor with carbon-based material can efficiently enhance the PEC activity by suppressing recombination, extending the excitation wavelength, or increasing the surface-active sites. [11][12][13] Since the pioneer report of graphene it become the most popular compound in the carbon-based family, 14 mainly attributed to the presence of a singular sp 2 carbon network that provides a privileged surface area, high conductivity and excellent electron mobility, ideal for applications in solar energy conversion.…”

Recent Advancement of p‐ and d‐Block Elements, Single Atoms, and Graphene‐Based Photoelectrochemical Electrodes for Water Splitting

“…The enhancement in photocurrent density is ascribed to various factors such as: 1) the band alignment of correctly oriented TiO 2 /graphene layers facilitates the separation of the photogenerated charge carriers, 2) the reduction of TiO 2 to Ti(OH) 3 in PEC conditions results in giving only −10 µA cm −2 , dictating that the major current emanates from the reduction of H + ions, but not due to the surface layer reduction, and 3) TiO 2 might have blocked hole and have 7%. [215] The performance of the newly synthesized material (CuBi 2 O 4 /rGO-4) is expected from the low charge-transfer resistance of 2.9k Ω, which improves the rapid charge transfer across the interface. The intimate contact between the directly grown material onto FTO additionally improves the charge mobility across the interface, and the adequately tuned band alignment of rGO and CuBi 2 O 4 further reduces the potential of water reduction.…”