Photocatalytic reforming of lignocellulose: A review

•Photocatalytic reforming processes for biomass in a relatively mild condition by solar energy is reviewed.•The generation mechanisms of hydrogen and fine chemicals are elucidated and discussed.•Different bond dissociations of lignin structure are examined and discussed over a variety of photocatalysts.•Perspectives are provided on the solar energy utilization and semiconductors for photocatalytic reforming.