Molecular Junctions on Polymeric Carbon Nitrides with Enhanced Photocatalytic Performance

Molecular catalysts (MC), namely homogeneous catalysts, have demonstrated great promise for efficient solar-to-chemical energy conversion in the hybrid system. However, the poor interfacial interaction between MC and photosensitizers (PS) impedes the efficient and fast interfacial electron transfer. To promote interfacial communication between PS and MC, a proof-of-concept method was developed for the combination of polymeric carbon nitride (PCN) PS with bipyridine cobalt [Co(bpy)32+ ] MC by covalent bonds, creating molecular junctions to promote interfacial electron transfer as confirmed by transient photoluminescence lifetime and electrochemical measurements. As a result, the binary photocatalyst [Co(bpy)32+ /BINA2 -CN] showed extensively enhanced photocatalytic activity such as H2 and CO2 reduction in comparison with the physical mixture of Co(bpy)32+ and PCN. This observation highlights the importance of construction of surface molecular junctions between PS and MC to accelerate the interfacial charge-carrier mobility and, consequently, improve the photocatalytic activity.