Three-dimensional nano-architecture of copper sulfide/nitrogen-doped titanium dioxide with dual heterojunction for
Riki Subagyo1, Masfufa Hildayanti1, Siti Fathimah Az-Zahra Dewi1
1Department of Chemistry, Faculty of Science and Analytic Data, Institut Teknologi Sepuluh Nopember, Surabaya, 60111, Indonesia.
Abstract:
A heterojunction in the semiconductor is thought to increase the transfer and separation of photoinduced charge carriers. However, morphology engineering is pivotal for achieving intimate contact between two photocatalysts for efficient charge-carrier transfer. In this work, a simple co-precipitation method yields intimate contact between CuS and N-TiO2 while maintaining the three-dimensional nanosphere morphology. The narrow band gap in the visible-light region (2.59-2.91 eV) is also observed. The intimate contact in CuS/N-TiO2 results in a type-II mechanism. Additionally, the plasmonic feature is attributed to the formation of Cu species in the composite, as confirmed by their presence in the Cu 2p core-level spectra and the observed absorption enhancement at 500 nm. Integrating a type-II heterojunction and a Schottky junction in CuS/N-TiO2 enables fast transfer and separation of photoexcited electron-hole pairs and reduces recombination. Consequently, the H2 photogeneration rate is improved, with the highest rate of 6248 µmol/g achieved with 0.2CuS/N-TiO2 as the photocatalyst. Besides, the durability test confirms that 0.2CuS/N-TiO2 maintains good stability throughout three photocatalytic H2 generation cycles. This finding implies that good stability of 0.2CuS/N-TiO2 is an essential factor for scaling up H2 generation to address energy issues. This direction provides insight into the morphological engineering of dual photocatalysts.
