Zengxin Pu,Bing Xiao,Siman Mao,Yingxue Sun,Dandan Ma,Hongkang Wang,Jun Zhou,Yonghong Cheng,Jian-Wen Shi
Photocatalytic hydrogen evolution from water splitting presents an attractive prospect in dealing with the energy crisis, but the low efficiency of charge separation and migration still seriously hinders its further practical application. Here, an acidified boron-doped g-C 3 N 4 (HBCNN) and cobalt porphyrin metal organic frameworks (CoPMOF) self-assembled two-dimensional and two-dimensional (2D/2D) hybrid photocatalyst is fabricated successfully. The resultant HBCNN/CoPMOF with optimum ratio exhibits a superior H 2 evolution rate of 33.17 mmol g −1 h −1 , which is 3.04 and 100.50 times higher than the single HBCNN and CoPMOF, respectively. It is found that a coordination connection has formed between CoPMOF and HBCNN through Co-N bond, and the interfacial Co-N bond then forms a pseudo-gap in the up-spin channel of electronic states, establishing an electron-hole separation mechanism. It is this electron-hole separation mechanism that contributes to a Z-scheme transport mode of photogenerated carriers, which greatly promotes the photocatalytic H2 production performance of HBCNN/CoPMOF heterostructure. This work may provide an idea for the design of heterojunction to improve the photocatalytic performance by constructing electron-hole separation through interfacial bond.
The reaction of porous γ-Al2O3 particles acting as both a sacrificial template and an aluminum source with 1,4-naphthalene diacid (H2NDC) resulted in the formation of γ-AlOOH@Al(OH)(1,4-NDC) composites, in which ZIF-67 was then loaded by the in situ crystallization method, leading to the formation of γ-AlOOH@Al(OH)(1,4-NDC)@ZIF-67 composites. The deliberately designed composite was used to separate H2/D2 at 77 K in a 1 m chromatographic column. The results demonstrated that the optimized composite can achieve the effective separation of H2/D2 in gas chromatography due to the additive effects of kinetic sieving and chemical affinity quantum sieving of Al(OH)(1,4-NDC) and ZIF-67. By optimizing chromatographic separation conditions, the resolution R reached 2.02 with the separation time t = 7.72 min. The composite also showed satisfactory repeatability and reproducibility.
The Mo-nonstoichiometry, oxygen vacancy, and S incorporation into Bi-Mo bimetallic oxide enhance the activity by creating defects that improve charge carrier separation efficiency and narrow bandgap energy. Oxygen vacancies synergistically attired nonstoichiometric and Mo-deficient and O-deficient Bi 2 Mo 3-x (S,O) 12-y oxysulfide (Mo-/O-deficient Bi 2 Mo 3 (S,O) 12 ) is found by a one-pot facile method to enhance the photocatalytic H 2 evolution and pollutant reduction via in-situ generated protons. The best Mo-/O-deficient Bi 2 Mo 3 (S,O) 12 catalyst with x = 0.75 and oxygen vacancy content of 27.6 % produced 480.87 µmol/h H 2 with 25 mg catalyst and achieved AQE of 14.26 % at λ = 420 nm, whereas reduced 88.9 % 4-NP and 91.6 % RhB by in-situ generated protons. Bi-non-stoichiometry leads to Mo 4+ and oxygen vacancy formation and creates active reaction sites of oxygen vacancy and active surface oxygen. These enhancements benefit photogenerated carrier separation efficiency and fast electron transfer and achieve Mo-/O-deficient Bi 2 Mo 3 (S,O) 12 with superb PHER. Therefore, non-stoichiometry and sulfur doping into Bi 2 Mo 3 O 12 bimetallic oxide is a promising approach for designing novel and synergistically defect-attired oxysulfide photocatalysts.
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