Magnetic-thermal external field activate the pyro-magnetic effect of pyroelectric crystal (NaNbO3) to build a promising multi-field coupling-assisted photoelectrochemical water splitting system

Rationalizing the external field advantage and manipulating more carrier separation is of great significance for expanding the research of external field-assisted photoelectrochemical (PEC) water splitting. Hence, we choose NaNbO3 material with pyroelectric properties for the realization of an efficient multi-field coupled-assisted PEC water splitting system using magnetic and temperature fields for the first time. Detailed experimental results show that the enhancement of photoelectric performance by magnetic fields seems to be limited. However, it is amazing that the coupling effect of magnetic and thermal field triggers the generation of pyro-magnetic effect, which breaks the limitation of non-radiative recombination of magnetic field manipulated carriers, and significantly improves the performance of PEC water splitting. The multi-field coupling drive the current density of the photoanode to span to 0.45 mA at 1.23 V vs. RHE (3 times higher than photocurrent). The first principle density functional theory (DFT) calculation is combined with experimental tests to fundamentally understand the interrelationship between crystal structure changes, charge density distribution and external fields, and the effect on catalytic performance. This research provides insights into the interaction mechanism between external fields and the radiative/non-radiative recombination of manipulating carriers. Insights are provided for the establishment of a multi-field coupling-assisted PEC water splitting system.