“…4. Under acidic conditions (pH < 4.0), it is difficult for -NH 3 + to form hydrogen bonds with PCP by -O-H/N, while -C]O also could easily form hydrogen bonds with the molecular state of PCP (-C]O/H), as well as -N-H/Cl, 39,40 -N-H/O hydrogen bonds and p-p interaction with the GO sheets (Fig. 4a).…”