A two-dimensional Cu(II) metal-organic framework and its g-C3N4 heterojunction composite for high efficient photodegradation of organic dyes

Abstract

A two-dimensional Cu(II) MOF {[Cu2(OH)(mtrb)(suc)1.5(H2O)2]·H2O·0.5DMA}n (Cu(mtrb)) (mtrb = 1,3-bis((1,2,4-triazol-4-ylmethyl)benzene, H2suc = succinic acid, DMA = N, N-dimethylacetamide) was obtained using solvothermal synthesis. Cu(mtrb) has a two-dimensional (6,3) network with the point symbol of 63. A series of Cu(mtrb)/wt%g-C3N4 composites were obtained by coupling Cu(mtrb) and semiconductor g-C3N4 to give heterojunctions by the grinding method. The composite samples were investigated with XRD, FT-IR, SEM, EDS, XPS, TGA, UV–Vis, PL and EIS to analyze the purity, functional groups, surface morphology, elemental distribution, valence electron, thermal stability, visible-light absorption and electron-hole pair separation status. Photocatalytic degrade methylene blue (MB), methyl orange (MO) and rhodamine B (RhB) were investigated. Cu(mtrb) can degrade 93.6% MB in 30 min, 87.0% MO in 135 min and 92.0% RhB in 90 min. Cu(mtrb)/10%g-C3N4 could degrade 96.2% MB in 15 min, 87.0% MO in 45 min and 92.3% RhB in 60 min, respectively. The coupling of Cu(mtrb) with g-C3N4 resulted in the formation of heterojunctions in Cu(mtrb)/wt%g-C3N4 composites and inhibited the rapid recombination of electron-hole pairs. The main reactive species for MB degradation were •OH and h+. Cu(mtrb) and Cu(mtrb)/10%g-C3N4 composites are the good photocatalysts.