Assembling γ-graphyne surrounding TiO₂ nanotube arrays: an efficient p–n heterojunction for boosting photoelectrochemical water splitting

Abstract

Photoelectrochemical water splitting is an excellent strategy for hydrogen generation, and it is pivotal to develop photoanodes with proficient sunlight harvesting, rapid charge separation, and enhanced electron injection efficiency. In...

Recent Advances in Self‐Supported Semiconductor Heterojunction Nanoarrays as Efficient Photoanodes for Photoelectrochemical Water Splitting

“…Regarding PEC OER enhancement using metal-free secondary semiconductors, Qiu et al recently reported construction of p-n heterojunctions by functionalization of TiO 2 nanotube arrays with γ-graphyne nanosheets (Figure 11d). [69] It can be seen that the addition of γ-graphyne increased the photocurrent density of the TiO 2 nanotube arrays (0.44 mA cm− 2 ), with 0.3-graphyne/TiO 2 (0.75 mA cm −2 ) having the optimal γ-graphyne loading (Figure 11e). The enhanced PEC performance was attributed to good band alignment between TiO 2 and γ-graphyne for charge separation, as well as more efficient light absorption (Figure 11f).…”

“…[57] This issue can be alleviated in semiconductor heterojunction systems, as the built-in electric field at the heterogeneous interface enables efficient charge carrier separation. [91] To this end, many narrow bandgap semiconductors, such as In 2 S 3 (2.1 eV), [57] Cu 2 O (2.17 eV), [53,80] Fe 2 O 3 (2.2 eV), [68] CeO 2 (2.4 eV), [46] CdS (2.42 eV), [70,73,74,92] graphyne (2.65 eV), [69] ZnSe (2.6 eV), [78] C 3 N 4 (2.7 eV) [48,61,79,93] and PbTiO 3 (2.75 eV), [76] have been hybridized with TiO 2 , leading to large enhancements in PEC OER performance.…”

“…In addition to conventional transition metal compounds (such as metal oxides, sulfides, and nitrides), metal-organic frameworks (MOFs) and metal-free semiconductors (e.g., graphyne and C 3 N 4 ) have also been used as sensitizers to improve the PEC efficiency of TiO 2 nanoarrays. [48,61,69,79,81,82,93] As a class of porous inorganic-organic hybrid materials, MOFs are crystalline materials with metal centers (cations or clusters) as nodes and organic ligands as linkers. [95] The compositional flexibility of MOFs, both node and linker, allows the optical band gaps in MOF semiconductors to be tuned from 1.0 to 5.5 eV.…”

Recent Advances in TiO2‐based Photoanodes for Photoelectrochemical Water Splitting

“…Very recently, Qiu et al. assembled γ‐graphyne surrounding TiO 2 nanotube arrays with an efficient p‐n heterojunction for boosting photoelectrochemical water splitting [155] . Moreover, graphene quantum dots (GQDs) with sizes of less than 10 nm can behave as a photosensitizer donating electrons to the CB of TiO 2 (Figure 13a–b) [156,157] …”

“…[154] Very recently, Qiu et al assembled γgraphyne surrounding TiO 2 nanotube arrays with an efficient pn heterojunction for boosting photoelectrochemical water splitting. [155] Moreover, graphene quantum dots (GQDs) with sizes of less than 10 nm can behave as a photosensitizer donating electrons to the CB of TiO 2 (Figure 13a-b). [156,157] On the other hand, heterostructures of TiO 2 with other graphene-like 2D materials are also intensively studied, especial for 2D transition metal dichalcogenides (TMDs) such as MoS 2 and MoSe 2 .…”