Rational construction of dual cobalt active species encapsulated by ultrathin carbon matrix from MOF for boosting photocatalytic H2 generation

Dual cocatalyst which integrates the merits of metal and metal oxide has been endowed with competitive advantages over noble metals for achieving efficient H2 evolution. In this case, developing spatially separated dual cocatalyst in carbon substrate with more efficient charge extraction and separation would be beneficial for further enhancing the photocatalytic activity. Herein, we utilized ultrathin two-dimensional (2D) Co-based MOF (Co-MOF) nanosheets as specific precursors for preparing carbon matrix encapsulated dual cobalt active species (Co and CoOx) on the surface of CdS for high-efficient photocatalytic H2 evolution under visible-light irradiation. The fundamental roles of 2D-MOF derived carbon matrix towards rational construction of dual cobalt active species have been visualized by combining a series of in-situ and ex-situ temperature-dependent analytic strategies. The carbon matrix as well as co-existed dual cobalt active species bring great improvement on charge carrier transportation and photogenerated electron-hole separation for enhanced photocatalytic activities, and an approximate 12.5-fold enhancement of H2 generation performance from 0.161 mmol h−1 of CdS to 1.997 mmol h−1 of the newly formed CdS-Co-CoOx@C with the apparent quantum efficiency of 43.7 % at 420 nm has been achieved. This work might provide the basic understanding and new opportunities in manipulating MOF structure through pyrolysis to fabricate high efficient cocatalysts for versatile photocatalytic reactions.