Photocatalytic activity of 2D copper porphyrin metal-organic framework for visible light overall water splitting

A 2D cupper tetrakis (4-carboxyphenyl)prophyrin metal-organic framework has been prepared and used as photocatalyst for overall water splitting, measuring under visible light irradiation (λ>450 nm) at one sun power a H2 production rate of 120 molH2 gcatalyst-1 h-1 that is among the highest ever reported. While the 2D Cu porphyrin MOF undergoes substantial degradation in 3 h upon UV irradiation (320-380 nm) exposed to the air, it appears to be photo stable under the conditions of the overall water splitting and visible light exposure, exhibiting similar temporal profiles for H2 and O2 evolution. Photocurrent experiments and band energy measurements indicates that the photocatalytic efficiency derives from an efficient charge separation in the visible region (apparent electron charge extraction efficiency at 540 nm of 0.1 %) and adequate alignment of the redox potential of the conduction (-0.59 V vs. NHE) and valence (+1.48 V vs. NHE) bands for water splitting.