Visible light driven hydrogen evolution using external and confined CdS: Effect of chitosan on carriers separation

Both fast recombination of photogenerated electron-hole pairs and quick photocorrosion limit CdS's application in hydrogen production. To address this dilemma, herein, we designed and synthesized a millimetre-sized chitosan-CdS xerogel bead photocatalyst (CXB@CdS) to expound the mechanisms of photocorrosion resistant and enhanced photocatalytic H-2 production. -NH2 and -OH groups of chitosan contribute to the spatial separation of photogenerated electron-hole pairs lead to inhibition of CXB@CdS photocorrosion, which guaranteed stable HER performance for 55 h. Directional migration of photogenerated holes from valence band (VB) of CXB@CdS to the highest occupied molecular orbital (HOMO) of chitosan was demonstrated due to the existence of lone pair electrons on -NH2 and -OH groups. This work can shed some light on the mechanism of natural polymers with rich functional groups modifying metal sulfides for effective photocorrosion inhibition and highly enhanced photocatalytic activities.