oxygen evolution of BHx gradually increased, with the highest
oxygen evolution rate reaching 183.2 µmol h−1
g−1 for BH400,
which is almost twice that of pristine g-C3N4 (98.6 µmol h−1
g−1
).
However, with calcination temperature further increased up
to 450 and 500 °C, BHx (x = 450 and 500) shows photocatalytic activities much decreased and even lower than the pristine g-C3N4. That is to say, the introduction of boron dopants
and nitrogen defects should be optimized to achieve an excellent photocatalytic activity for oxygen evolution. With Co(OH)2
cocatalyst loaded onto BHx (see Experimental Section for
details in the Supporting Information), all the samples show
significant increase in photocatalytic activity (Figure 5d). Specifically, the oxygen evolution rate of BH400 was dramatically
increased to 561.2 µmol h−1
g−1
with an apparent quantum
yield of 3.7% at 380 nm, which is much higher than that of
most reported g-C3N4 (Table S5, Supporting Informati