The preparation of ternary hexagonal boron carbon nitride (h-BCN) nanosheets was carried out by doping biomass glucose in situ into hexagonal boron nitride (h-BN). With this method, the construction of a two-dimensional (2D) semiconductor with tunable bandgap and characteristic adsorption ability toward organic molecules was achieved by maintaining the specific structure of h-BN and p-p interactions toward aromatic compounds. The ternary 2D h-BCN nanosheets worked effectively not only as a desirable adsorbent but also as an activator to benzene. Furthermore, the unique 2D h-BCN nanosheets were found to work as effective photocatalysts to convert benzene into phenol with less over-oxidation, leading to the development of a new type of Fenton oxidation reaction as the one-step visible light-driven hydroxylation of benzene. An optimal yield of 14.0% and its selectivity of 88.3% for the photocatalytic production of phenol from benzene were achieved by using h-BCN in the presence of FeCl3 and H2O2 in sustaining the same reactivity even after 4 cycles. This present study reports the latest development of phenol production from benzene by applying 2D h-BCN nanosheets as an artificial photosynthetic catalyst.