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

Abstract

We report a Cu2O/CdS/ZnO photoanode constructed by coupling Cu2O and CdS nanoparticles on ZnO nanotube arrays (NTAs) via combining chemical bath deposition with successive ionic-layer adsorption and reaction. Integrating the merits of the superior ability of Cu2O and CdS to harvest visible light, dual heterojunctions, type-II band structure, a p-n junction, and ordered tubular structure, the photoanode exhibits simultaneous significant improvements in the visible light absorption, charge separation, hydrogen generation, and stability. At 0.4 V versus Ag/AgCl under AM 1.5 G irradiation, the photoanode achieves a photocurrent density of 7 mA/cm2, which is 2.3-fold higher than that of CdS/ZnO heterojunction NTAs. Furthermore, under AM 1.5 G illumination without bias potential, the photoanode achieves an average hydrogen generation rate of 134 μmol/h, which is 1.5 times that of single-heterojunction CdS/ZnO NTAs. The highest solar-to-hydrogen conversion efficiency of the Cu2O/CdS/ZnO photoanode is 2.8% at 0.6 V vs. RHE, 1.6 times that of the CdS/ZnO NTAs.

Nanoarray Structures for Artificial Photosynthesis

“…Forming dual-bandgap (heterojunction and homojunction) nanoarray structures that combine advantages of the two constituents has been recognized as another attractive method for promoting charge transport. [47,[186][187][188] In addition to having the advantages mentioned above for single-bandgap nanoarray structures, dual-bandgap nanoarray structures can also promote charge separation to minimize the energy-wasteful electronhole recombination owing to the built-in electric field formed at the interfacial region of two constituents. [176,189,190] Compared to the single-bandgap systems, dual-bandgap systems with an ideal theoretical efficiency of 41% are more likely to achieve the minimum efficiency requirement of 10% for practical solar water splitting.…”

The doping of B in ZnO/CdS for enhanced visible-light H2 production

“…8 In particular, the ZnO/CdS heterostructure was proved to be an efficient collocation. [9][10][11][12][13][14][15] ZnO was considered to be an ideal semiconductor material to construct a heterojunction with CdS, and it could suppress the photocorrosion of CdS. The ZnO semiconductor was selected to couple with CdS to obtain a ZnO/CdS heterojunction, which could have a better photocatalytic efficiency due to the wide band gap of ZnO.…”

Facile One-Pot In Situ Synthesis and Characterization of a Cu2O/Cu2(PO4)(OH) Binary Heterojunction Nanocomposite for the Efficient Photocatalytic Degradation of Ciprofloxacin from Aqueous Solution under Direct Sunlight Irradiation

“…Recently, various approaches have been employed to improve the chemical and physical properties of nanomaterials. − In order to overcome the above-expressed drawbacks of Cu 2 (PO 4 )­(OH) and Cu 2 O structures, formation of a p–n heterojunction nanocomposite can be a potential solution to increase the photocatalytic efficiency. Prior to this, various heterojunction composites of Cu 2 (PO 4 )­(OH) and Cu 2 O materials have been fabricated, such as Cu 2 (OH)­PO 4 /g-C 3 N 4 , TiO 2 –Cu 2 (OH)­PO 4 , Cu 2 (OH)­PO 4 /reduced graphene oxide, Cu 2 (OH)­PO 4 /Cu, Cu 2 O/CdS/ZnO, Cu 2 O/ZnO/Ag 3 PO 4 , and Cu 2 O/Bi/Bi 2 MoO 6 . ,,,,− The combination of Cu 2 (PO 4 )­(OH) and Cu 2 O, due to the generation of the p–n junction heterostructure, can induce a synergistic effect between them and subsequently produce more strong oxidizing agents for outstanding photocatalytic performance under sunlight irradiation.…”