Enhanced photocatalytic hydrogen production performance of K0.5Na0.5NbO3-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 ABO₃-type K_0.5Na_0.5NbO₃ (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–0.04NdNiO₃ 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. [ABSTRACT FROM AUTHOR]