Photoelectrochemical (PEC) water splitting is one of the most desirable techniques to harvest clean chemical energy from abundant solar energy. However, the anodic half reaction, i.e., water oxidation, is complicated due to the involvement of multiple electrons in this process. Herein, stable WO 3 nanoblocks with the monoclinic phase have been modified by the incorporation of hexagonal boron nitride quantum dots (h-BNQDs) to improve the photogenerated electron−hole separation and additionally to hinder the charge recombination process. The photocurrent density (J) value for the modified WO 3 photoanode by incorporation of BNQDs has been found to be 1.63 mA/cm 2 at the potential of 1.23 V RHE , which is approximately 2.4-fold higher than the bare WO 3 photoanode. The enhancement in photocurrent density is mainly due to the hole extraction property of BNQDs on the surface of the WO 3 nanoblocks. A 2-fold increment in photogenerated charge carrier density (N D ) value has been achieved due to better charge separation of electron−hole pairs in the modified system, confirmed by the Mott−Schottky (MS) plot. The present work demonstrates a unique, low-cost strategy for enhancement of PEC water oxidation by modification of the photoanode with hole extracting agents.

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

Harvesting clean energy from sunlight is a promising and desirable path to resolve the energy challenge through photoelectrochemical (PEC) water splitting. Herein, we report the design and synthesis of a stable hematite photoanode with sequential metal and nonmetal incorporation to resolve the limiting factors such as low carrier density and high charge recombination for its practical applications. Comprehensive morphological, optical, and photoelectrochemical properties of the doped hematite photoanodes are presented to understand the mechanisms by which the dopant incorporation impacts the photoelectrode performance. It is found that with controlled calcination temperature metal and nonmetal incorporation not only increases the carrier density but also facilitates faster charge transfer. The charge carrier density of the photoanode derived from Mott–Schottky plot shows an increase by an order of magnitude, i.e., from 5.1 × 1019 to 5.7 × 1020 cm–3, with dual modification. The dual modified hematite photoanode shows a photocurrent density of 2.56 mA/cm2 at 1.23 V vs RHE, which is ∼5-fold higher as compared to that of the bare hematite photoanode. We believe that the present method of designing and fabricating the hematite photoanode by sequential incorporation of metal and nonmetal will provide an economical and efficient strategy for better solar energy conversion.

Rational design of hierarchical nanocomposites is a promising approach for efficient energy harvesting and conversion. A noble-metal-free ternary hierarchical composite, Cd0.5Zn0.5S-g-C3N4-MoS2, has been developed. Materials were chosen based on their relative band-edge alignments and they were studied as a composite for photocatalytic properties. The photocatalytic activity was evaluated by measuring the rate of photodriven H2 evolution with concomitant degradation of organic pollutants, such as Rhodamine B. Optimization of the loading of g-C3N4 and MoS2 onto Cd0.5Zn0.5S results in an enhanced yield of hydrogen evolution by ∼120% (Cd0.5Zn0.5S-g-C3N4) and ∼197% (Cd0.5Zn0.5S-g-C3N4-MoS2) compared to bare Cd0.5Zn0.5S. The ternary hybrid, Cd0.5Zn0.5S-g-C3N4-MoS2 resulted in an apparent quantum yield (AQY) of 38% at 420 nm. The significant improvement in photocatalytic performance in the composite can be attributed to enhanced interfacial charge transfer of electrons from g-C3N4 to Cd0.5Zn0.5S and MoS2. We surmise that the close proximity of the energies of conduction band edge for each component in the ternary composite promotes better charge separation.

A low overpotential of 220 mV at 10 mA cm–2 comparable to the benchmark RuO2 catalyst with a Tafel slope of 62 mV per decade having a turnover frequency of 3.17 s–1 is attained for strontium-doped lanthanum manganite (La0.7Sr0.3MnO3) coupled with cobalt phosphate (Co-Pi) for the oxygen evolution reaction (OER). Impedence spectroscopic analysis of La0.7Sr0.3MnO3/Co-Pi suggests a favorable charge-transfer resistance results in efficient charge carrier extraction. A Faradaic yield close to unity (98%) for the OER suggests that the oxygen evolved during the reaction is solely from the water oxidation.