Nano-Au and Ferroelectric Polarization Mediated Si/ITO/BiFeO3 Tandem Photocathode for Efficient H2 Production

For efficient utilization of solar light during photoelectrochemical (PEC) water splitting, tandem photoelectrodes comprising a wider bandgap top semiconductor stacked above a smaller bandgap one have been proposed in the previous studies. However, the photocurrent is usually limited due to the blocked transfer of photogenerated carriers on the interface between the semiconductors. Here, this study constructs an Si-pnn(+)/ITO/Au/BiFeO3 (BFO) hybrid photocathode catalyzed by MoS2/Pt with an intension to fulfill the efficient transfer of photogenerated electrons from Si to electrode surface. This study reveals how the local surface plasmonic resonance effect of Au nanoparticles and the depolarization electric field of BFO enhance the PEC reactivity of the photocathode, and also the catalytic effect of the combined MoS2/Pt catalyst. Remarkably, the photocathode exhibits an onset potential of 1.3 V versus reversible hydrogen electrode (RHE), and the photocurrent at 0 V versus RHE can be up to -9.1 mA cm(-2) under 100 mW cm(-2) Xe-lamp illuminations. Such a unique design represents a general strategy to enhance the PEC performance of a tandem photoelectrode where the energy bands are not so matched on the interfaces, and therefore extends the scope of the tandem architectures.