Self-Templated Conversion of a Self-Healing Metallogel into an Active Carbon Quasiaerogel: Boosting Photocatalytic CO2 Reduction by Water

Healing and photosynthesis are two prime examples of intrinsic aptitude in the incredibly diverse plant kingdom. Inspired by nature, the development of new materials with the intrinsic ability of healing and artificial photosynthesis is of current interest. In this regard, herein, a new waterborne self-healing metallogel (Nd-SHMG) along with a self-templated carbonization strategy is presented for the synthesis of a neodymium@nitrogen-doped carbon quasiaerogel (Nd@NCA) catalyst. The stiffness of the metallogel (self-healing, self-sustaining, and molding behavior) can be controlled by tuning the synthetic conditions. A metal-free nitrogen-doped carbon quasiaerogel (MF@NCA) was also prepared via partial removal of the metal from the Nd@NCA catalyst. The as-synthesized Nd@NCA and MF@NCA catalysts were composed of highly porous 2D sheets which are grown on top of each other, adopting a 3D foam-type structure. The porosity (∼9 fold) and the CO2 adsorption capacity (∼8 fold) can be gradually increased ‘on demand’ by partial removal of the metal ion from the pristine Nd@NCA. The as-synthesized catalysts exhibit excellent photocatalytic activity for CO2 conversion into CO (∼17–24 μmol g–1) with over ∼87% selectivity without adding sacrificial agents. Isotopic carbon-labeled (13CO2) in situ diffuse reflectance infrared Fourier transform spectroscopy analysis was performed, and a plausible mechanism was outlined for photocatalytic CO2 reduction to CO. With this work, we introduce a facial and feasible strategy to prepare a Nd-SHMG and their conversion into active bifunctional carbon quasiaerogel-based catalysts, which can adsorb and convert CO2 selectively into CO without adding sacrificial agents in the presence of water and light.