Two-dimensional ultra-thin nanosheets optimize the surface reaction dynamics and photo/pyro-generated carrier transfer of NaNbO3 for an efficient pyro-photo-electric catalytic system

Abstract

The slow surface reaction dynamics and charge transfer of pyroelectric materials employed in photoelectrochemical water splitting remain key aspects restricting their application. Therefore, we propose a strategy that integrates a 2D ultra-thin (<5 nm) nanosheet Co(OH)₂ layer on NaNbO₃ to optimize the surface reaction dynamics and provide an unobstructed photo/pyro-generated carrier transfer path for a pyro-photo-electric catalytic system. Under the stimulation of light and heating–cooling cycles, The resultant NaNbO₃/Co(OH)₂ composite photoanode exhibits a high current density of 1.68 mA cm⁻² at 1.23 V_RHE and a negative onset potential of 0.25 V_RHE, which is about 2.63 times higher with a 150 mV cathodic shift compared to that of the bare photoanode. Detailed experimental results indicate that the synergism between the pyroelectric effect and surface reaction dynamics optimization can improve the photo/pyro-generated carrier transfer dynamics. The synergism regulation of internal and external carriers builds an unimpeded carrier transmission channel. This work reports an inexpensive Co(OH)₂ layer as a route to optimize the surface reaction dynamics of pyroelectric crystals, providing a novel and promising strategy for the more efficient use of solar, thermal, and electrical energy for water splitting.