Dapeng Lu

A cocatalyst-free CdS nanorod/ZnS nanoparticle composite for high-performance visible-light-driven hydrogen production from water

Highly efficient, visible-light-induced hydrogen (H2) production via water splitting can be achieved without the help of a cocatalyst by using a noble-metal-free core–shell photocatalyst, in which zinc sulfide (ZnS) nanoparticles as the protective shell are anchored on the surface of cadmium sulfide nanorods (CdS NRs). Due to the close interfacial contact of component semiconductors, the electronic structure of CdS is strongly coupled with that of ZnS nanoparticles, leading to efficient transfer of charge carriers between them and the improvement of the CdS photostability. The CdS/ZnS NR photocatalyst showed much higher catalytic activity for H2 production than CdS NRs and ZnS under visible light irradiation (λ > 420 nm), which is probably due to fast transfer of the photogenerated charge carriers and/or electron tunneling in the one-dimensional core–shell nanorod structure. Under optimal conditions, the highest hydrogen evolution rate reached 239 μmol h−1 mg−1, which is much greater than ZnS and CdS NRs and also among the best cocatalyst-free photocatalysts for H2 production. The average apparent quantum yield can be achieved as ∼16.8% after 8 h of irradiation (monochromatic light at 420 nm ± 5 nm). A possible mechanism for the photocatalytic reaction based on CdS/ZnS NRs is also discussed.

Enhanced photocatalytic H2 production on cadmium sulfide photocatalysts using nickel nitride as a novel cocatalyst

Photocatalytic hydrogen production using solar energy offers a clean and sustainable pathway for future energy supply. Herein, we report nickel nitride (Ni3N) as a novel cocatalyst on cadmium sulfide nanorod (CdS NR) semiconductors to enhance photocatalytic hydrogen production in water. The Ni3N cocatalyst was grown by a facile in situ growth method. Under optimal conditions, the hydrogen production rate can be improved more than 10 times by introducing an appropriate amount of Ni3N on CdS NRs. PL spectra and photoelectrochemical measurements suggest that faster interfacial charge transfer between Ni3N and CdS may be the key factor for the enhanced photocatalytic activity.

Molecular cobalt–salen complexes as novel cocatalysts for highly efficient photocatalytic hydrogen production over a CdS nanorod photosensitizer under visible light

An efficient photocatalytic system is highly demanded for the production of hydrogen fuel through water splitting. Herein, we report an artificial photocatalytic system made of low-cost materials for high-performance H2 production from water. The new system contains semiconductors (CdS nanorods) as the photosensitizer, a cobalt–salen complex as the H2 evolution cocatalyst, and Na2S and Na2SO3 as sacrificial electron donors. Under optimal conditions, the highest hydrogen evolution turnover number reached 64 700 after 37 hours and the rate was 106 μmol h−1 mg−1, which is much higher than when using CdS NRs and also is among the best for photocatalytic systems using molecular cocatalysts for H2 production. The highest apparent quantum yield (AQY) was ∼29% at 420 nm. Steady state photoluminescence (PL) spectra and time-resolved photoluminescence (TRPL) decay spectra revealed that the system allows effective electron transfer from the excited CdS NRs to the cobalt–salen complex for highly efficient H2 production.

A Large π‐Extended Carbon Nanoring Based on Nanographene Units: Bottom‐Up Synthesis, Photophysical Properties, and Selective Complexation with Fullerene C70

Herein we report the organoplatinum-mediated bottom-up synthesis, characterization, and properties of a novel large π-extended carbon nanoring based on a nanographene hexa-peri-hexabenzocoronene (HBC) building unit. This tubular structure can be considered as an example of the longitudinal extension of the cycloparaphenylene scaffold to form a large π-extended carbon nanotube (CNT) segment. The cyclic tetramer of a tetramesityl HBC ([4]CHBC) was synthesized by the reaction of a 2,11-diborylated hexa-peri-hexabenzocoronene with a platinum complex, followed by reductive elimination. The structure of this tubular molecule was further confirmed by physical characterization. Theoretical calculations indicate that the strain energy of this nanoring is as high as 49.18 kcal mol-1 . The selective supramolecular host-guest interaction between [4]CHBC and C70 was also investigated.

Pyrolyzed cobalt porphyrin-based conjugated mesoporous polymers as bifunctional catalysts for hydrogen production and oxygen evolution in water

In this present study, a series of cobalt porphyrin-based conjugated mesoporous polymers (CoP-nph-CMP, n = 2, 3, 4) were fabricated as catalyst precursors to generate bifunctional catalysts via pyrolysis (CoP-nph-CMP-800, n = 2, 3, 4) for both the oxygen evolution reaction (OER) and the hydrogen evolution reaction (HER). Among these catalysts, CoP-2ph-CMP-800 exhibited the best catalytic activity with quite a low overpotential for both the OER (η = 370 mV for 10 mA cm-2) and the HER (η = 360 mV for 10 mA cm-2). Moreover, their excellent bifunctional catalytic performance was also explored in the overall water splitting test (η = 760 mV for 10 mA cm-2).

Synergistic Effect of a Molecular Cocatalyst and a Heterojunction in a 1 D Semiconductor Photocatalyst for Robust and Highly Efficient Solar Hydrogen Production

Photocatalytic production of hydrogen by water splitting is a promising pathway for the conversion of solar energy into chemical energy. However, the photocatalytic conversion efficiency is often limited by the sluggish transfer of the photogenerated charge carriers, charge recombination, and subsequent slow catalytic reactions. Herein, we report a highly active noble-metal-free photocatalytic system for hydrogen production in water. The system contains a water-soluble nickel complex as a molecular cocatalyst and zinc sulfide on 1D cadmium sulfide as the heterojunction photocatalyst. The complex can efficiently transport photogenerated electrons and holes over a heterojunction photocatalyst to hamper charge recombination, leading to highly improved catalytic efficiency and durability of a heterojunction photocatalyst- molecular cocatalyst system. The results show that under optimal conditions, the average apparent quantum yield was approximately 58.3 % after 7 h of irradiation with monochromatic 420 nm light. In contrast, the value is only 16.8 % if the molecular cocatalyst is absent. Such a remarkable performance in a molecular cocatalyst-based photocatalytic system without any noble metal loading has, to the best of our knowledge, not been reported to date.

A novel symmetrically multifunctionalized dodecamethoxy-cycloparaphenylene: synthesis, photophysical, and supramolecular properties

In the present study, we report the synthesis of a novel symmetrically multifunctionalized cycloparaphenylene (CPP), dodecamethoxy-[9]CPP (ring[9]arene), through nickel-mediated macrocyclization and subsequent reductive aromatization reactions. The electron-donating methoxy groups were introduced onto the curved precursor at an early stage to avoid the problem of non-selective functionalization of CPPs. Compared to [9]CPP, the present dodecamethoxy-[9]CPP shows a significant red shift (>73 nm) in the fluorescence spectrum. In addition, theoretical calculations revealed its increased torsion angles and ring strain (71.01 kcal mol−1) compared with its unsubstituted counterpart.

A Three‐Dimensional Capsule‐like Carbon Nanocage as a Segment Model of Capped Zigzag [12,0] Carbon Nanotubes: Synthesis, Characterization, and Complexation with C70

Herein we report the synthesis and photophysical and supramolecular properties of a novel three-dimensional capsule-like hexa-peri-hexabenzocoronene (HBC)-containing carbon nanocage, tripodal-[2]HBC, which is the first synthetic model of capped zigzag [12,0] carbon nanotubes (CNTs). Tripodal-[2]HBC was synthesized by the palladium-catalyzed coupling of triboryl hexabenzocoronene and L-shaped cyclohexane units, followed by nickel-mediated C-Br/C-Br coupling and subsequent aromatization of the cyclohexane moieties. The physical properties of tripodal-[2]HBC and its supramolecular host-guest interaction with C70 were further studied by UV/Vis and fluorescence spectroscopy. Theoretical calculations revealed that the strain energy of tripodal-[2]HBC was as high as 55.2 kcal mol-1 .