Enhancing photocatalytic activity of tantalum nitride by rational suppression of bulk, interface and surface charge recombination

• Published in: Applied catalysis. B, Environmental Environmental, 2019-06, Vol.246, p.195-201
• Main Authors: Xiao, Mu, Wang, Zhiliang, Luo, Bin, Wang, Songcan, Wang, Lianzhou
• Format: Article
• Language: English
• Subjects: Catalysis; Catalysts; Catalytic activity; Charge transfer; Co-catalyst; Cobalt oxides; Doping; Electron mobility; Energy conversion; Hollow structure; Hydrogen production; Magnesium; Magnesium oxide; Migration; Photocatalysis; Photocatalysts; Platinum; Recombination; Redox reactions; Solar energy; Solar energy conversion; Surface charge; Surface defects; Surface passivation; Tantalum; Tantalum nitride; Tantalum nitrides
• ISSN: 0926-3373; 1873-3883
• DOI: 10.1016/j.apcatb.2019.01.053

[Display omitted] •A synergistic approach in suppressing charge recombination is designed for Ta3N5 photocatalyst.•The charge separation in bulk, interface and on surface of Ta3N5 photocatalyst is drastically improved through the multi-strategy approach.•A ˜ 38 times higher H2 evolution rate (56.3 μmol h−1) on new hollow Ta3N5 than that of bulk counterpart is achieved. Rational design of photocatalysts is essential to achieve efficient solar energy conversion. For narrow bandgap Ta3N5 photocatalyst, various charge recombination occurring in the bulk, interface and on the surface significantly impairs its activity for solar hydrogen (H2) generation. Herein, a synergistic engineering approach is designed to solve this critical recombination challenge. First, hollow spherical structure of Ta3N5 with Mg doping is prepared to not only reduce the charge migration distance and increase the surface area, but also increase the electron mobility for facilitated charge transfer. Second, an MgO nano-layer covers the surface of hollow Ta3N5 structure to passivate surface defects, thus promoting the interfacial charge transfer between Ta3N5 and co-catalysts. Finally, dual co-catalysts (Pt/CoOx) for redox reactions are loaded onto the hollow Ta3N5 structure to reduce the surface recombination and overcome the sluggish surface reaction. Remarkably, the combination of hollow structure, Mg2+ doping, MgO interfacial layer, and dual co-catalysts effectively improves the charge separation and transfer in Ta3N5 photocatalyst. This newly designed photocatalyst exhibits a considerably improved H2 generation performance of 56.3 μmol h−1 under simulated sunlight, compared to that of reference Pt/Ta3N5 hollow spheres.