Photocatalysis has been extensively investigated for energy and environmental applications. As the key role in photocatalysis, a great variety of photocatalysts have been developed towards low cost, low toxicity, and high activity. Titanium dioxide has been regarded as the most popular photocatalyst, yet cannot harvest visible light, the bigger energy contribution than UV from sunlight. Recently, graphitic carbon nitride (g-C₃N₄) was discovered as a polymeric photocatalysis with the promising nature of metal-free and visible light response. Because of the powerful reduction ability, g-C₃N₄ has been readily for water splitting and CO₂ reduction. This talk, however, focuses on its photocatalytic oxidation ability. To this end, a number of modification methods were introduced. Particularly for maintaining the metal-free nature, different nanocarbons were used to fabricate completely metal-free, g-C₃N₄-based photocatalysts for degradation of organic pollutants in water.