Enhanced photocatalytic hydrogen production performance of K0.5Na0.5NbO3-based ferroelectric semiconductor ceramics by Nd/Ni modification at A/B sites and polarization

• Published in: New journal of chemistry 2024-03, Vol.48 (12), p.5495-5505
• Main Authors: Sun, Qingyi, Yuan, Changlai, Liu, Xiao, Zhang, Xiaowen, Zhao, Jingtai, Zhou, Changrong, Rao, Guanghui, Su, Kaiyuan, Wang, Dong
• Format: Article
• Language: English
• Subjects: Charge efficiency; Charge transport; Electric fields; Energy bands; Energy gap; Ferroelectric materials; Ferroelectricity; Hydrogen production; Photocatalysis; Polarization; Room temperature; Semiconductor materials; Valence band
• ISSN: 1144-0546; 1369-9261
• DOI: 10.1039/d3nj05806a

In the photocatalytic processes of ferroelectric semiconductor materials, how to induce a depolarized electric field (Edp) by polarization to reduce the electron–hole recombination rate is still a big problem. Here, the ABO3-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–0.04NdNiO3 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 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.