Engineering g-C3N4 with CuAl-layered double hydroxide in 2D/2D heterostructures for visible-light water splitting
Hanane Boumeriame1, Alexey Cherevan2, Dominik Eder2
1LSRE-LCM - Laboratory of Separation and Reaction Engineering - Laboratory of Catalysis and Materials, Faculty of Engineering, University of Porto, Rua Dr. Roberto Frias s/n, 4200-465 Porto, Portugal; ALiCE - Associate Laboratory in Chemical Engineering, Faculty of Engineering, University of Porto, Rua Dr. Roberto Frias, 4200-465 Porto, Portugal; Laboratory of Chemical Engineering and Valorization of Resources (LGCVR-UAE/L01FST), Faculty of Sciences and Techniques, University Abdelmalek Essaadi, Tangier, Morocco; Institute of Materials Chemistry, Technische Universität Wien (TU Wien), Getreidemarkt 9, Vienna 1060, Austria.
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CuAl layered double hydroxide (LDH) and polymeric carbon nitride (g-C3N4, GCNN) were assembled to construct a set of novel 2D/2D CuAl-LDH/GCNN heterostructures. These materials were tested towards H2 and O2 generation from water splitting using visible-light irradiation. Compared to pristine materials, the heterostructures displayed strongly enhanced visible-light H2 evolution, dependent on the LDH content, which acts as a cocatalyst, replacing the benchmark Pt. The optimal LDH loading was achieved for 0.2CuAl-LDH/GCNN that exhibited an increased number of active sites and showed a trade-off between charge separation efficiency and light shading, resulting in a 32-fold increase in the amount of evolved H2 compared with GCNN. In addition, the 0.2CuAl-LDH/GCNN heterostructure generated 1.5 times more O2 than GCNN. The higher photocatalytic performance was due to efficient charge carriers' separation at the heterojunction interface via an S-scheme (corroborated by work function, steady-state and time-resolved photoluminescence studies), enhanced utilisation of longer-wavelength photons (>460 nm) and higher surface area available for the catalytic reactions.
