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Advanced functional materials: molecular heterojunction composite photocatalyst with high visible light photocatalytic performance for hydrogen production at room temperature and atmospheric pressure

wallpapers News 2020-10-28

photocatalytic decomposition of water to produce hydrogen is a new technology which can realize the direct conversion of solar energy hydrogen energy plays an increasingly important role in the development of hydrogen energy. Graphite like carbon nitride (PCN) as a star material of photocatalyst has many advantages such as simple preparation stable physical chemical properties environment-friendly so on. However due to the electronic structure of PCN its narrow visible light absorption range high probability of photo generated carrier recombination seriously limit the development of PCN in the field of photocatalytic hydrogen production. In addition the research on photocatalytic hydrogen production by PCN is mostly limited to vacuum conditions which greatly increases the cost of photocatalytic hydrogen production limits the process of its industrial application. In view of this problem Professor Shi Yumeng of Shenzhen University Professor Xu Qinghua of National University of Singapore their research team have made important progress in photocatalytic hydrogen production at room temperature pressure.

are the most effective methods for constructing PCN based composite photocatalysts which are combined with donor acceptor organic semiconductors to construct polymer heterojunctions. However due to the small contact area between polymer heterojunctions it is difficult to greatly improve the transfer separation of photogenerated carriers between composite materials. In order to better solve this problem the team used PCN as the substrate material to modify the small organic molecules of donor - π - acceptor Containing Triphenylamine benzene ring benzothiadiazole units constructed the type II molecular heterojunction composite photocatalyst. Small organic molecules PCN have similar π - conjugated structure. Through π - π stacking they are uniformly dispersed on the surface of PCN which greatly improves the contact area between molecular heterojunctions. The modification of donor - π - acceptor greatly improves the absorption performance of the composite photocatalyst in the visible light region. In this heterojunction the enhancement of the efficiency of photo generated carrier separation mainly comes from two aspects: (1) the extremely poor energy in type II heterojunction promotes the electron transfer to PCN the hole transfer to small organic molecules; (2) the Triphenylamine Unit can accelerate the electron transfer hole capture as an electron donor hole acceptor. At the same time the photo absorption performance photo generated carrier separation efficiency were improved which greatly improved the photocatalytic hydrogen production performance of the composite photocatalyst. The photocatalytic hydrogen production rate was up to 4.63 mmol H-1 g-1 under simulated sunlight at room temperature atmospheric pressure which was higher than the photocatalytic hydrogen production performance of PCN based photocatalyst reported in literature at room temperature atmospheric pressure.

the PCN heterojunction composite photocatalyst constructed by this work has achieved high activity in decomposing water to produce hydrogen under normal temperature pressure which is expected to realize the industrialization of PCN based photocatalyst in the field of photocatalytic hydrogen production.

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