CdS/Au/Ti/Pb(Mg1/3Nb2/3)(0.7)Ti0.3O3 photocatalysts and biphotoelectrodes with ferroelectric polarization in single domain for efficient water splitting

摘要

The construction of efficient photocatalysts for water splitting is still challenging, mainly due to the unexpected recombination of photogenerated carriers. Ferroelectric polarization-induced charge separation of photo catalysts has been demonstrated as an effective method for improving photocatalytic performance. However, ferroelectric domains in existing works are random before polarization-switching, which results in lower polarization electric field intensity and limits the charge separation efficiency. Here, we report that the spontaneous ferroelectric polarization in a single domain for efficient charge separation over a representative semiconductor CdS, in the form of CdS/Au/Ti/Pb(Mg1/3Nb2/3)(0.7)Ti0.3O3 (CdS/Au/Ti/PMN-PT), for water splitting in absence of any cocatalyst or external voltage. The photocurrent value of the positive polarized CdS/Au/Ti/PMN-PT yields 1.70 mA.cm(-2), which is about 20 times higher than the value of the non-polarized sample. In addition, a biphotoelectrode cell composed of a positively and a negatively polarized CdS/Au/Ti/PMN-PT was constructed. A considerable solar-to-hydrogen conversion efficiency of 0.19% was achieved. It was found that the interfacial resistance and the surface reaction kinetics may be the main factors governing the photocatalytic performance. This work not only provides a strategy to promote charge separation but also develops a new biphotoelectrode cell capable of obtaining efficient solar water splitting.