Studies On Photocatalysts Based On Graphtic Carbon Nitride

Graphtic like carbon nitride(g-C3N4),a visible-light responded photocatalyst with the bandgap of 2.7 eV,is a polymer aggregated with the two-dimensional nanosheets which are composed of tri-s-triazines interconnected via tertiary amines.And exfoliating bulk g-C3N4 into nanosheets with proper methods would endow it more unique propoties to promote it's photocatalytic activities.In our work,We put forword a new method to exfoliate bulk g-C3N4 into g-C3N4 nanosheets with the aid of isopropanol,and the final product possess high photocatalystic activity.And the mechanism of the effect of the added IPA was tried to explain with some characteristics.The details are described in the following aspects:1)Bulk g-C3N4*was preapared with the calcining melamine,and then was exfoliated into g-C3N4 NS*by thermal oxidation etching process.Different products were obtained with different calcination weight of bulk g-C3N4*,and finally we found that g-C3N4 NS*owned the best photocatalytic activity when the weight of bulk g-C3N4*is 0.1 g.For comparison,g-C3N4 NS-T and g-C3N4 NS-U was synthesized with the precursor of thiourea and urea using the same method,and found that the photoactivity of g-C3N4 NS*was only a little difference with g-C3N4 NS-T and g-C3N4 NS-U.But the productivity of g-C3N4 NS*are nearly two times higer than that of g-C3N4 NS-T and g-C3N4 NS-U,meaning that g-C3N4 NS*owns a better development foreground.2)g-C3N4 NS was obtained by adding IPA into both the melamine calcination and the bulk g-C3N4 exfoliation proccess.Compared with g-C3N4 NS*,not only the photocatalytic hydrogen evolution rate was improved two times and reached to 1501 ?mol·g-1·h-1(g-C3N4 NS*of 479 ?mol·g-1h-1),but also the degradation ability was greatly enhanced which could degrade the RhB in 45 min compeletly(g-C3N4 NS*of 31.1%remained).3)g-C3N4 NS(1)and g-C3N4 NS(2)was synthesized with IPA added into the melamine calcination process and exfoliation process respectively.Combined with the comparation of bulk g-C3N4 and bulk g-C3N4*,the function of IPA in experimental aspects can be conjectured.4)Tert-Butanol(t-BuOH)and triethanolamine(TEOA)were selected as scavengers for ·OH and holes,and 10 vol%of them were added into the RhB solutions for degradation,respectively.And some characterizations were used to deduce the effect of IPA together with experiments.5)NiS and MoS2 Some other materials were selected as the dopant to prepare composites with g-C3N4 NS and g-C3N4NS*.And the products were characterized with the photocatalytic hydrogen evolution.The results showed that g-C3N4 NS obtained with our method owned the most advantages in prepare composites based on g-C3N4 nnanosheets.