Highly efficient utilization of light and charge separation over hematite photoanode achieved through noncontact photonic crystal film for photoelectrochemical water splitting
The trade-off problem between light absorption and charge collection under lower band-bending (bias) is extremely difficult to resolve in water splitting on photoelectrodes. Although the uses of metallic back-reflector, antireflection coating, and textured substrate and light absorber enable the improvement of light utilization efficiency, these methods still suffer from high cost, complex fabrication process, especially, incompetent separation of photogenerated carriers. Here taking hematite (α-Fe2O3) photoanode as a model, we report that noncontact photonic crystal (PC) film consisted of silica nanoparticles and ethoxylated trimethylolpropane triacrylate (ETPTA) resin can significantly enhance photoelectrochemical (PEC) activity of the photoelectrode. Specifically, more than 250 mV cathodic shift of onset potential and 4-times larger photocurrent at 1.0 V versus reversible hydrogen electrode (RHE) were achieved over the α-Fe2O3-PC photoanode hybrid system, compared with pristine α-Fe2O3 photoanode. Our work showed that PC film not only boosted light absorption of α-Fe2O3 layer but also improved its charge transfer efficiency under light illumination. These new findings of synergetic effect will open a new avenue to design high-performance solar energy conversion device.