The band edge alignments based on HSE06 calculations can be rationalized by regulating the VBM and CBM by the vacuum potentials, which are taken as the potential energy at the edge of the vacuum layer. The impact of pH on the electrode potentials of HER and OER can be further digitized by E(H + /H 2 ) = -4.44 eV + pH× 0.059 eV and E(O 2 /H 2 O) = -5.67 eV + pH×0.059 eV, respectively . However, the combined impact of pH value to the performance of photocatalysts is complex, not limited to its additional effects on the thermodynamics of HER and OER . Many theoretical studies only evaluated the photocatalytic activity of 2D polymers without considering the effect of different pH conditions .