Heterogeneous p–n Junction CdS/Cu₂O Nanorod Arrays: Synthesis and Superior Visible-Light-Driven Photoelectrochemical Performance for Hydrogen Evolution

Abstract

Heterogeneous p-n junction CdS/CuO nanorod arrays have been fabricated by using a facile successive ionic-layer adsorption and reaction process to grow CuO nanoparticles on the surface of ordered CdS nanorod arrays. The heterogeneous p-n junction nanorod arrays exhibit superior photoelectrochemical performance for hydrogen (H) generation and high stability under visible-light irradiation. The highest photocurrent density achieved by heterogeneous nanorod array photoelectrode is 4.2 mA cm in a sacrificial NaS and NaSO mixture electrolyte solution at 0 V versus Ag/AgCl, which is 4 times higher than that of a pure CdS nanorod array photoelectrode. In addition, the heterogeneous nanorod array photoelectrode achieves an incident photon conversion efficiency value of 40.5% at 470 nm. The photocatalytic hydrogen generation rate of the heterogeneous nanorod array photoelectrode reaches up to 161.2 μmol h, around 3-fold increase compared to that of a bare CdS photoelectrode. Furthermore, the heterogeneous p-n junction CdS/CuO nanorod arrays show an excellent stability under long light illumination of 7200 s. The improved photoelectrochemical performance, photocatalytic activity, and excellent stability of the heterogeneous nanorod array photoelectrode resulted from the efficient separation of photoinduced electron-hole pairs, which is achieved by the synergistic effects of CdS, CuO, p-n junction, and an inner electric field in the photoelectrode. The present work provides a new strategy to fabricate a heterogeneous photoelectrode. This facile strategy is expected to be utilized to fabricate electrodes of other materials for highly efficient solar-driven water splitting application.

One‐Step Transformation from Cu2S Nanocrystal to CuS Nanocrystal with Photocatalytic Properties

“…Metal sulfides such as CoS x and ZnS are also widely used in electrochemical energy storage . Moreover, one of the most notable merit of metal sulfides is their relatively smaller bandgaps, which make sure that many of them can directly utilize visible light . Especially in recent years, the metal sulfide based photocatalysts (CuS, ZnS, CdS et al) have been extensively used in wastewater treatment field because of its greater light absorption range and excellent photocatalytic performance …”

Towards Visible LED Illumination: ZnO‐ZnS Nanocomposite Particles

“…But combination with ZnS “results in an effective surface band gap narrowing to 2.8 eV.”(440 nm) . Such combinations of sulfides and oxides are published for cupper (II) in the field of solar light supported hydrogen production . The minimum of necessary energy or the maximum in the absorbed wavelength is in the range of a one to one composition of Oxygen to Sulphur ions .…”

Periodic FTO IOs/CdS NRs/CdSe Clusters with Superior Light Scattering Ability for Improved Photoelectrochemical Performance

“…The co‐deposition of CdS and CdSe QDs to form CdS/CdSe nanojunction has been successfully achieved, such as CdSe/CdS/TiO 2 /indium‐tin‐oxide nanowire array, and CdS/CdSe QDs co‐sensitized TiO 2 nanocable arrays, CdS/CdSe co‐sensitized brookite H:TiO 2 nanostructures, CdS/CdSe co‐sensitized ZnO porous nanotube arrays . Compared to CdS QDs or CdS films, CdS NRs have better PEC performance due to the presence of direct pathways for electron transportation and its larger specific surface area . Although the combination of CdSe nanostructures with CdS NRs has been investigated for PEC applications, the utilization of 3D FTO IOs as a host skeleton to further improve their PEC performance has yet to be investigated.…”