Improved photocatalytic efficiency and stability of CdS/ZnO shell/core nanoarrays with high coverage and enhanced interface combination

Self-Assembled Vertically Aligned Hetero-Epitaxial ZnO/CdS Core/Shell Array by all CBD Process: Platform for Enhanced Visible-Light-Driven PEC Performance

“…In addition, the CdS is not expected to be suitably stoichiometric and its epitaxial matching with ZnO is not straightforward. It seems that these two drawbacks of the synthesis process may be responsible for the reported low photocurrent densities, up to 6.0 mA/cm 2 . ,− There are reports of additional layer on top of CdS as a passivation layer, ,, viz. Au, NiO, ZnFe 2 O 4 , for enhancing the photocurrent but the same have not been helpful (see Table ).…”

“…In the case of core/shell type device structures, an appropriate approach to efficiently absorb light in the visible region is to create the staircase band-aligned heterostructures by decorating ZnO NRs with QDs of narrow band gap semiconductors such as ZnO/PbS, , ZnO/In 2 S 3, , ZnO/ZnS, ZnO/PbSe, ZnO/CdSe, ZnO/CdS, − etc. Therefore, it may be a fascinating approach to enhance the visible light driven photoelectrochemical performance based on the structurally superior and suitably band aligned core–shell semiconductors.…”

“…In the NR-based devices, the ZnO NRs have been largely synthesized by the hydrothermal process, ,,,,− which involves the use of high temperatures (80–200 °C) and high pressure (>1 atm) with a long deposition time that is typically tens of hours. This makes the hydrothermal process time-consuming and uneconomical.…”

“…This makes the hydrothermal process time-consuming and uneconomical. Further, hexamethylenetetramine (HMT) is used in the process to achieve the c -axis oriented vertically standing ZnO NRs. ,,,,− The HMT has a 2-fold role, as a source of OH – ions (through its thermal degradation) and to introduce a strong steric hindrance effect for inducing the anisotropic growth along the c -axis, thereby ensuring the vertical arrangement. As widely reported in the literature, the CdS shell has been prepared by a different technique, viz.…”

A Dual-Heterojunction Cu2O/CdS/ZnO Nanotube Array Photoanode for Highly Efficient Photoelectrochemical Solar-Driven Hydrogen Production with 2.8% Efficiency

“…Furthermore, the type-II band alignment and internal electric field (IEF) established by a p-n junction promote efficient charge transfer and separation, suppressing the charge recombination rate. In addition, when CdS is coupled with ZnO to form a ZnO/CdS heterojunction, the band alignments of ZnO and CdS lead to the establishment of a type-II heterojunction, as demonstrated in previous works. − Thus, a ternary Cu 2 O/CdS/ZnO structure with dual heterojunctions will fully utilize the merits of the type-II band alignment and the p-n junction as well as the superior visible light harvesting ability of CdS and Cu 2 O to improve PEC water splitting properties. So, this ternary heterostructure is expected to achieve drastically enhanced PEC water splitting properties and find potential applications in the efficient, cost-effective conversion of solar energy into electrical or stored chemical energy.…”