Magnetic field-augmented photoelectrochemical water splitting in Co3O4 and NiO nanorod arrays

Effective charge separation is crucial for improving the sensitivity of photoelectrochemical studies. Here, we provide an immense magnetic field-based electron spin polarization approach for an efficient charge carrier separation. We have fabricated NiO and CoO thin film and nanorod arrays by electron beam evaporation glancing angle method followed by annealing in a two-zone furnace. The photoelectrochemical performance was investigated for NiO and CoO samples in the presence and absence of a magnetic field. The NiO and CoO nanorods array samples exhibit better absorption compared with the thin film samples. The CoO and NiO nanorod arrays showed the highest photocurrent density of 0.12 and 0.55 mA/cm in a magnetic field. The superior photoelectrochemical response of NiO and CoO nanorods in a magnetic field could be ascribed to the limitation of non-radiative recombination of carriers manipulated by Lorentz force and spin polarization. Furthermore, the electrochemical impedance spectra of NiO and CoO nanorod arrays in a magnetic field show the least charge transfer resistance. This study sheds light on the interaction process between external fields and radiative/non-radiative recombination of manipulating carriers. Thus, the application of a magnetic field presents an efficient and versatile approach to enhance the performance of photoelectrodes in solar water splitting.