BiVO₄ Polaron-Hopping State-Induced Low-Bias Spintronic Water Splitting Device

Both n-type and p-type BiVO4 photoelectrodes demonstrate a high performance in water splitting devices, with an ultrahigh solar to hydrogen energy conversion performance as high as 6.77 and 7.51%, respectively. The external quantum efficiencies of the n-type and p-type BiVO4 photoelectrodes under 520 nm laser irradiation are 54.52 and 48.38%, respectively. Besides, over 49 L of hydrogen gases evolved from the n-type BiVO4 photoelectrode and over 32 L of hydrogen gases from the p-type BiVO4 photoelectrode. With the polaron surface state and the polaron-hopping energy level, the p-type BiVO4 demonstrated over 50% spin polarization rate since ℏ/–ℏ angular momentum-modulated circular polarization serves as the spintronic excitation light source. The hole-trapping Fermi level of the p-type BiVO4 affords the water splitting devices a shorter path for hole transportation than the n-type BiVO4.