Unraveling the role of single layer graphene as overlayer on hematite photoanodes

Interface engineering of nanoceramic hematite photoelectrode for solar energy conversion

“…The measurements were carried out under no bias and 1.23 V RHE applied potential with 1 mol/L NaOH electrolyte. The measured signal was analyzed using a digital oscilloscope (Tek‐tronic, TDS 2022C) 16 …”

“…These parameters are coupled in a way that each efficiency is dependent to the other, and the balance among the modifier additions is a duty not easily to be achieved. In this regard, intense investigations have been dedicated to select elements or materials to overcome hematite limitations, by boosting the charge separation ( η sep ) and surface ( η cat ) efficiencies by doping, 10‐15 carbon‐based modifications, 16,17 passivation layers, 18‐20 and others 21‐25 …”

“…These parameters are coupled in a way that each efficiency is dependent to the other, and the balance among the modifier additions is a duty not easily to be achieved. In this regard, intense investigations have been dedicated to select elements or materials to overcome hematite limitations, by boosting the charge separation (η sep ) and surface (η cat ) efficiencies by doping, [10][11][12][13][14][15] carbon-based modifications, 16,17 passivation layers, [18][19][20] and others. [21][22][23][24][25] From the η sep perspective, the addition of Ti, Sn, and Sb elements have demonstrated to be promising candidates on enhancing the electronic conductivity and, consequently, the efficiency in charge separation.…”

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

“…The incorporation of graphene with no or negligible defects in the form of a large area sheet is highly required to maintain or enhance its electrical conductivity, electron mobility and carrier density. 70 In this way, SLG has high transparency (97.7%) at visible light ( λ = 550 nm); the Fermi level band alignment between SLG and the photoactive material makes it convenient for use in photoelectrochemical applications. 71 It is expected that the SLG presence would not lead to a change in the photoanode optical properties due to its very thin layer and high transparency.…”

“…The passivation effect of the surface states after SLG incorporation on the top of the photoanode, resulted in an increased lifetime of the photogenerated holes. 70 Additionally, as a consequence of the strong interaction between SLG and the photoanode, it was observed an efficient charge carrier separation and better hole accumulation at the photoanode surface, 70,74 increasing the water oxidation efficiency. 70 Although much higher photocurrent can be obtained after the deposition of SLG on the top of metal-oxides films, it is important to highlight that in this case different methods for SLG deposition should be taken into account for better interaction of the semiconductor with the graphene material, in such a way that not only the photoanode surface would be benefited by the SLG presence, but the whole composite.…”