Ultrathin 2D/2D ZnIn₂S₄/g‐C₃N₄ Nanosheet Heterojunction with Atomic‐Level Intimate Interface for Photocatalytic Hydrogen Evolution under Visible Light

Abstract

hydrogen combustion only produces water. Therefore, hydrogen as a promising energy for the future development can help to meet the future energy needs and solve environmental problems. [4,5] Semiconductor-based photocatalytic water splitting utilizing renewable solar energy for hydrogen production is considered to be a feasible technology with great promise. [6][7][8][9] According to the research of titanium dioxide (TiO 2 ) single crystal in photoelectrochemistry, Fujishima and Honda [10] pioneered the field of semiconductor photocatalysis. However, the wide band gap of metal oxide such as ZnO, [11][12][13][14] SnO 2 , [15][16][17][18] Nb 2 O 5 , [19][20][21] etc., makes them only respond to near-ultraviolet or ultraviolet light, resulting in low efficiency of solar energy. In fact, visible light accounts for 43% of sunlight, while ultraviolet ray accounts for merely 4%. Therefore, developing visible light-driven photocatalysts attracts widespread attention for purpose of making better use of solar energy. [22][23][24] Graphite carbon nitride (g-C 3 N 4 ) is an attractive nonmetallic conjugated polymer semiconductor, which has been extensively applied in photocatalytic water splitting because of its attractive electronic structure, excellent thermal and chemical stability, unique 2D layered structure, suitable band gap, low toxicity, etc. [25][26][27] However, the actual application of the original g-C 3 N 4 still suffers from the limitations of underutilization of visible light, lacking of catalytic active sites, hydrophobic surface, low carrier mobility, and rapid recombination of photoinduced carriers. [28,29] For addressing these challenges, various strategies have been adopted so as to improve the photocatalytic performance of the original g-C 3 N 4 , such as nanostructure design, [30][31][32] doping of metallic and nonmetallic elements, [33][34][35][36] construction of heterojunctions, [37][38][39][40] copolymerization, [41][42][43] defect engineering, and dye sensitization. [44,45] Among them, the controllable synthesis of nanoscale morphology is one of the resultful means. Because of its characteristics including appropriate porosity, massive surface groups for anchoring, large specific surface area, slim thickness and as well as high aspect ratio, semiconductor nanosheets describe a brilliant future. [46] Therefore, 2D g-C 3 N 4 nanosheets may significantly improve the photocatalytic activity. [47,48] Besides, integration with other semiconductors to build heterojunctions is considered to be a reliable means. [49][50][51] Ultrathin 2D/2D heterostructures usually Designation of high-efficiency water splitting photocatalyst is still a challenge in converting solar energy into chemical fuels. Heterojunction can inhibit recombination of carriers which is considered to be a reliable strategy to improve photocatalytic performance on water splitting. In this work, a "face-to-face" 2D tight heterostructure is constructed by growing ZnIn 2 S 4 nanosheets on g-C 3 N 4 nanosheets. Due to the ultrathin 2D structure...

Improve the Photocatalytic Hydrogen Production Using ZnS@ZnO Twin‐Junction Structure with Isoelectronic Traps

“…Photocatalytic water splitting to produce hydrogen is one of the promising ways to solve the energy shortage issue. [1,2] The photocatalytic process is divided into three steps: [3] the absorption of sunlight (I), the separation and transport of electronhole pairs (II), and the redox reaction (III). In view of these processes, many methods have been adopted to improve photo catalysis activity, such as loading photosensitizer, [4,5] loading precious metal, [6] loading single atoms, [7] constructing heterojunction/homojunction, [8] constructing p-n junction, [9] spatial separation [4,10] and doping, [11] etc.…”

Selective deposition of cocatalyst NiS on a g-C3N4/ZnIn2S4 heterojunction for exceptional photocatalytic H2 evolution

“…Heterojunction construction is a widely adopted approach to regulate photo-excited charges' dynamic behaviors, thus suppressing the recombination of carriers. [19][20][21][22][23][24][25] So far, various g-C 3 N 4 based heterojunctions have been reported for the photogeneration of H 2 , such as WO 3 /g-C 3 N 4 , 26,27 TiO 2 /g-C 3 N 4 , 28,29 COF/g-C 3 N 4 , 30 g-C 3 N 4 /ZnIn 2 S 4 31,32 and so on. Among them, 2D/2D g-C 3 N 4 /ZnIn 2 S 4 has drawn much attention due to the matched band structure and the sufficient interface area, which is beneficial for the interfacial charge transfer.…”

Porous graphitic carbon nitride with high concentration of oxygen promotes photocatalytic H2 evolution

“…Researchers adopted surfactants, block polymers and ionic liquids as soft templates to synthesize microporous g-C 3 N 4 . 29–31 Mesoporous silica, silica nanoparticles and CaCO 3 nanosphere were selected as hard templates to prepared mesoporous g-C 3 N 4 . 32–34 The obtained porous architecture increased surface area, exposed active sites and promoted mass transfer, thus enhancing the photocatalytic performance of g-C 3 N 4 .…”