Enhanced photocatalytic hydrogen production performance of K 0.5 Na 0.5 NbO 3 -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 K 0.5 Na 0.5 NbO 3 (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 (∼2.75 eV) and high residual polarization value (∼11.56 μC cm −2 ). After high-field poling, the hydrogen production rate of the sample in the full spectrum reaches 926.28 μmol g −1 h −1 , indicating an increase of approximately 5 times compared to the 170.45 μmol 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 E dp 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.