Engineering g-C3N4 with CuAl-layered double hydroxide in 2D/2D heterostructures for visible-light water splitting

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.