Monoclinic BiVO 4 is recognized as a promising photoanode for water oxidation, but its relatively wide bandgap energy (E g %2.5 eV) and poor charge transport limit the light absorption (η abs ) and charge separation (η sep ) efficiencies, thus resulting in low photocurrents. To solve these drawbacks, here the η abs  η sep product has been decoupled by combining W-doped BiVO 4 and V 2 O 5 rods (E g %2.1 eV) for simultaneously increasing the light harvesting and the charge separation in photoanodes under back-side illumination. In this strategy, V 2 O 5 rods maximize the light absorption and hole transport throughout the W-BiVO 4 film, making more holes to achieve the V 2 O 5 /W-BiVO 4 /H 2 O interface to trigger the water oxidation reaction with photocurrents as high as 6.6 mA cm À2 at 1.23 V RHE after 2 h reaction. Notably, under back-side illumination, the W-BiVO 4 /V 2 O 5 photoanode exhibited η abs  η sep of 74.5 and 93.0% at 0.5 and 1.23 V RHE , respectively, the highest values reported up to date for BiVO 4 -based photoelectrodes. This simple strategy brings us closer to develop efficient photoanodes for photoelectrochemical water splitting devices.

The conventional chemical methods to produce graphene using strong oxidizing agents produce toxic gases during synthesis; therefore, these methods do not meet the principles of green chemistry. In this work, an alternative top-down method for the synthesis of a few layers of graphene sheets has been produced by a Fenton reaction- (a mixture of Fe2+/H2O2) assisted exfoliation process in water using graphite flakes as a starting material. Based on X-ray diffraction data and Fourier transform infrared (FTIR), Raman spectroscopy, and transmission electron microscopy measurements, it is proposed that the oxidation of graphite by Fenton chemistry facilitates the exfoliation of graphene sheets under mild sonication. Subsequent chemical reduction with ascorbic acid produced a few layers of reduced graphene oxide. Compared to Hummers’ method, the Fenton reagent has similar exfoliation efficiency, but due to the Fenton reagent’s preference to react with the edges of graphite, the chemical reduction can lead to the formation of less defective reduced graphene oxides. Moreover, since Fe and H2O2 are cheap and environmentally innocuous, their use in large-scale graphene production is environmentally friendlier than conventional methods that use toxic oxidizing agents.

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