Development of a magnetic nanohybrid for multifunctional application: From immobile photocatalysis to efficient photoelectrochemical water splitting: A combined experimental and computational study

[Display omitted] •A newly magnetic nanohybrid is prepared using Fe2O3 which is easily separable and recoverable.•Newly developed nanohybrid shows efficient visible-light photocatalysis and photoelectrochemical current in the presence of visible light.•The nanohybrid has been embedded in a stainless steel mesh for real-life prototype applications.•The experimental results are duly verified by first principles DFT calculations. Engineering of highly efficient nanomaterials with visible-light photocatalytic activity that are easily separable and recoverable from treated water is the ultimate goal in the ongoing research in the field of photocatalysis. On the other hand, photoelectrochemical (PEC) water splitting is one of the most promising technologies for hydrogen production using solar light with the aim to build sustainable, renewable and green energy. Hematite (α-Fe2O3) is a promising material that offers both enhanced photocatalytic activity and PEC activity due to its electronic band structure, high chemical stability, great abundance, and low cost. Despite these promising properties, the application of this system is limited due to its very fast electron-hole recombination rate and low carrier mobility. Here we report the design and synthesis of a newly envisioned nanohybrid based on Fe2O3 and phthalocyanine. The nanohybrid is an essential component to reduce the charge carrier recombination rate of the system. As a result of it, the nanohybrid shows higher photocatalytic activity and acts as a better photoanode material for photoelectrochemical water splitting. The formation of the nanohybrid is established using a picosecond resolved optical technique as well as by Raman Spectroscopy. Ab-initio study on the similar modeled system has been performed to investigate the insight of various physical properties. Electron microscopy reveals a distinct change of morphology in the nanohybrid compared to pristine one. While the photocatalytic activity of the nanohybrid increased 1.5 times with respect to the pristine system, the Photoelectrochemical activity almost doubles in the hybrid system. For real-world applications, our developed nanohybrid has been deposited on an extended surface of a stainless-steel metal mesh (size 2 cm × 2 cm, pore size 150 μm × 200 μm). Such a prototype active filter containing an immobilized photocatalyst shows significant chemical filtration of MB (by a degradation process) along with a physical filtration by separating the su