Generalized Synthetic Strategy for Amorphous Transition Metal Oxides‐Based 2D Heterojunctions with Superb Photocatalytic Hydrogen and Oxygen Evolution

Abstract

2D amorphous transition metal oxides (a‐TMOs) heterojunctions that have the synergistic effects of interface (efficiently promoting the separation of electron−hole pairs) and amorphous nature (abundant defects and dangling bonds) have attracted substantial interest as compelling photocatalysts for solar energy conversion. Strategies to facilely construct a‐TMOs‐based 2D/2D heterojunctions is still a big challenge due to the difficulty of preparing individual amorphous counterparts. A generalized synthesis strategy based on supramolecular self‐assembly for bottom–up growth of a‐TMOs‐based 2D heterojunctions is reported, by taking 2D/2D g‐C3N4 (CN)/a‐TMOs heterojunction as a proof‐of‐concept. This strategy primarily depends on controlling the cooperation of the growth of supramolecular precursor and the coordinated covalent bonds arising from the tendency of metal ions to attain the stable configuration of electrons, which is independent on the intrinsic character of individual metal ion, indicating it is universally applicable. As a demonstration, the structure, physical properties, and photocatalytic water‐splitting performance of CN/a‐ZnO heterojunction are systematically studied. The optimized 2D/2D CN/a‐ZnO exhibits enhanced photocatalytic performance, the hydrogen (432.6 µmol h−1 g−1) and oxygen (532.4 µmol h−1 g−1) evolution rate are 15.5 and 12.2 times than bulk CN, respectively. This synthetic strategy is useful to construct 2D a‐TMOs nanomaterials for applications in energy‐related areas and beyond.

Self‐Assembly of Hollow, Pompon‐Like and Nanosheet‐Structured Carbon Nitride for Photodegradation of Tetracycline Hydrochloride

“…[1][2][3][4] However, the fast electron-hole (e − /h + ) recombination rate, low crystallinity, and small surface area limit largely its use in photocatalysis. [5,6] Many strategies including heteroatom doping, [7,8] metal deposition, [9,10] semiconductor coupling, [11][12][13] and morphology control [14] have been attempted to improve the photocatalytic performances of g-CN and got great success. Among them, the control of microstructure and morphology is an attractive route, which can yield changes in the crystallinity, the surface area, effects of reaction conditions on the activity of hp-CN-6, the best catalyst for the reaction, were investigated.…”

2D Amorphous CoO Incorporated g‐C3N4 Nanotubes for Improved Photocatalytic Performance

“…To reveal the carrier transfer mechanism of CN/a‐CoO‐0.2 and CN/Co 3 O 4 ‐0.1 heterojunction, the trapping experiment of active species based on the degradation of RhB was conducted. [ 29,53 ] Theoretically, CN and CoO (Co 3 O 4 ) can form a type‐II (type‐I) heterojunction. [ 27 ] Figure a1 shows that the addition of EA and BQ causes a significant decrease in degradation efficiency, indicating that holes and play a major role in the CN/a‐CoO‐0.2 catalytic process.…”

“…[27] The morphology control and energy band engineering synergistically construct 2D/2D type-II heterojunction is an effective method. [28][29][30][31] It can achieve effective separation of carriers while shortening the distance of the carriers participating in the reaction, and provide a larger specific surface area and a large amount of reactive site. [32][33][34][35] Considering the lone pair of N/O at the edge of CN, it is reasonable to be applied to anchor cobalt ions with empty orbitals on the surface of CN, so as to construct 2D/2D CN/a-CoO heterojunction, which not only inhibits the aggregation of CoO but also promotes the formation of a-CoO.…”

g‐C3N4‐Based 2D/2D Composite Heterojunction Photocatalyst

“…2D materials are featured with 2D microscopic morphologies, such as nanosheet, nanoflake, nanoplate, and nanoleaf. A variety of 2D photocatalysts, including metal oxides, [53] metal disulfide, [54] Bi-based compounds, [55] ternary chalcogenide, [56] and layered double hydroxide (LDH), [57] have been coupled with g-C 3 N 4 to construct g-C 3 N 4 -based 2D/2D heterojunction. Overall, the synthesis strategies of g-C 3 N 4 -based 2D/2D composites can be divided into two categories: combining the as-prepared g-C 3 N 4 and 2D photocatalyst and realizing the coupling in the preparation of g-C 3 N 4 or 2D photocatalyst.…”