Hematite photoanodes for water splitting from directed assembly of Prussian blue onto CuO-Sb2O5-SnO2 ceramics

We report the controlled layer-by-layer growth by the directed assembly of Prussian blue to form (via thermolysis) a functional hematite coating on the grain surfaces of porous CuO-Sb2O5-SnO2 ceramics. The impact of the hematite coating on the physicochemical properties of the ceramics is demonstrated through Raman spectroscopy, and photoelectric and electrochemical impedance measurements. The directed assembly of ionic layers described here is a promising approach for introducing thin film deposits into porous structures and modifying/tuning the photoelectrochemical properties of SnO2-based ceramic materials.

Interface designing of efficient Z-scheme Ti-ZnFe2O4/In2O3 photoanode toward boosting photoelectrochemical water oxidation

Ti-ZnFe₂O₄ photoanode has attracted extensive attention in photoelectrochemical (PEC) water oxidation due to its narrow band gap and good photostability. However, its low efficiency limits its development. Herein, we designed and constructed direct Z-scheme Ti-ZnFe₂O₄/In₂O₃ (Ti-ZFO/In₂O₃) photoanode. Under the interface electric field, photogenerated holes with stronger oxidation capacity on In₂O₃ are retained to participate in the water oxidation reaction, and the photocurrent density of Ti-ZFO/In₂O₃ is much higher than that of pure Ti-ZFO, reaching 2.2 mA/cm² at 1.23 V vs. RHE. Kelvin Probe, steady-state photovoltage spectroscopy (SPV), transient photovoltage spectroscopy (TPV) and in-situ double beam strategy were used to demonstrate the Z-scheme charge transfer mechanism of Ti-ZFO/In₂O₃ photoanode. Our work provides an effective scheme and technical means for further understanding the mechanism of interfacial charge transfer.

Microwave-assisted thermochemical conversion of Zr-FeOOH nanorods to Zr-ZnFe2O4 nanorods for bacterial disinfection and photo-Fenton catalytic degradation of organic pollutants

Herein, we report a CoO_x-loaded Zr-doped ZnFe₂O₄ (CoO_x/Zr-ZFO) NR photocatalyst synthesized by successive microwave and wet impregnation methods for bacterial inactivation and degradation of organic pollutants. For the first time, microwave treatment was used for Zn attachment on hydrothermally synthesized self-assembled Zr-FeOOH NRs to produce Zr-doped ZnFe₂O₄ (Zr-ZFO) NRs. The lowest bandgap energy (1.96 eV) enables for significant absorption in the visible light region, which helps to improve bacteria degradation inactivation efficiency. Further, various metal oxides (Cu, Ag and Co) were loaded onto the surface of photocatalysts (Zr-ZFO NRs) by a wet impregnation method. As-synthesized CoO_x/Zr-ZFO-3 NRs were systematically characterized and used as photocatalysts for inactivation of E. coli and S. aureus and degradation of organic pollutants. The CoO_x/Zr-ZFO-3 NR photocatalyst exhibited better inactivation efficiency (99.4 %) than other metal oxide-loaded Zr-ZFO NRs (Ag₂O_x-loaded Zr-ZFO NRs (33.6 %), CuO_x-loaded Zr-ZFO NRs (77.6 %)). Additionally, the optimum CoO_x/Zr-ZFO-3 NR photocatalyst showed 98.3 % and 98.1 % degradation efficiencies for BPA and orange II dye, respectively, under visible light irradiation (λ ≥ 420 nm). Therefore, this work affords a novel, simple and rapid approach for the development of photocatalysts which active in visible light for bacterial disinfection and organic degradation.