Enhanced photocatalytic hydrogen production performance of K_0.5Na_0.5NbO₃-based ferroelectric semiconductor ceramics by Nd/Ni modification at A/B sites and polarization

In the photocatalytic processes of ferroelectric semiconductor materials, how to induce a depolarized electric field (E-dp) by polarization to reduce the electron-hole recombination rate is still a big problem. Here, the ABO(3)-type K0.5Na0.5NbO3 (KNN) material is modified by Nd and Ni elements at A/B sites to narrow the band gap and maintain the room-temperature ferroelectric behavior. The 0.96KNN-0.04NdNiO(3) sample shows the narrowed band gap (similar to 2.75 eV) and high residual polarization value (similar to 11.56 mu C cm(-2)). After high-field poling, the hydrogen production rate of the sample in the full spectrum reaches 926.28 mu mol g(-1) h(-1), indicating an increase of approximately 5 times compared to the 170.45 mu mol g-1 h-1 of the unpoled sample. The improved performance of photocatalytic hydrogen production mainly results from the reduction of band gap and the formation of Edp after polarization. The change in the position of the top of the valence band after sample polarization reveals that high-field poling can improve charge transport efficiency by energy band bending.