Metal- and Carbon-Based Materials as Heterogeneous Electrocatalysts for CO2 Reduction.

Climate change caused by continuous rising level of CO2 and the depletion of fossil fuels reserves has made it highly desirable to electrochemically convert CO2 into fuels and commodity chemicals. Implementing this approach will close the carbon cycle by recycling CO2 providing a sustainable way to store energy in the chemical bonds of portable molecular fuels. In order to make the process commercially viable, the challenge of slow kinetics of CO2 electroreduction and low energy efficiency of the process need to be addressed. To this end, this review summarizes the progress made in the past few years in the development of heterogeneous electrocatalysts with a focus on nanostructured material for CO2 reduction to CO, HCOOH/HCOO-, CH2O, CH4, H2C2O4/HC2O-4, C2H4, CH3OH, CH3CH2OH, etc. The electrocatalysts presented here are classified into metals, metal alloys, metal oxides, metal chalcogenides and carbon based materials on the basis of their elemental composition, whose performance is discussed in light of catalyst activity, product selectivity, Faradaic efficiency (FE), catalytic durability and in selected cases mechanism of CO2 electroreduction. The effect of particle size, morphology and solution-electrolyte type and composition on the catalyst property/activity is also discussed and finally some strategies are proposed for the development of CO2 electroreduction catalysts. The aim of this article is to review the recent advances in the field of CO2 electroreduction in order to further facilitate research and development in this area.

Exploration of Graphitic-C3N4 Quantum Dots for Microwave-Induced Photodynamic Therapy.

Here, we report our new observations on graphitic-phase carbon nitride (g-C3N4) quantum dots (QDs) as agents for microwave induced photodynamic therapy (MIPDT). For the first time, we observed that singlet oxygen is produced in g-C3N4 QDs by microwave irradiation, which can be used for tumor destruction. The results of live/dead staining and flow cytometry show that g-C3N4 QDs based MIPDT can effectively kill cancer cells and promote tumor cell death. In addition, the cell viability and hemolysis tests in vitro indicate that g-C3N4 QDs have very low cell toxicity and possess excellent biocompatibility in the physiological environments. All these indicate that g-C3N4 QDs are promising for MIPDT, a new potential modality for cancer treatment.