Carbon nitride: An Interface driven organic semiconductor and its use in artificial photosynthesis and photoosmotic machines
Markus Antonietti, Max Planck Institute of Colloids and Interfaces, Potsdam, Germany
Some recent observations made polymeric graphitic Carbon Nitride a valuable extension to current semiconducting organic materials. This is due to the ease of synthesis, but also due to its extreme chemical stability. Made from urea under early-Earth conditions, as reported already by Justus Liebig in 1832, it just recently turned out to be a novel catalyst which- among other reactions- can even chemically activate CO2 or photochemically turn water into hydrogen, oxygen, or more valuable compounds. This opens the door to a new chemistry on the base of a sustainable and most abundant polymers. Current apparent quantum yields partly exceed 0.85, i.e. the transduction from light energy to chemical energy is good enough for a real world. I will focus here on the special physical chemistry of a functional solid-liquid interface, revoking the importance of “old colloid chemistry” also for the fashionable new topics.
I will report in this presentation mostly new polyionic members of the Carbon Nitride family which are most stable organic semiconductors, highly crystalline and have HOMO potential down to +2.7 Volt. This accesses not only a cocatalyst-free full artificial photosynthesis, but also a new deep oxidation chemistry realizing a number of organic chemistry dream reactions that could previously be not performed.
Single atom functionalization is a biomimetic tool that even extends reactivity space, and even ions as Mg2+ or Ca2+ change electronic properties and substrate binding and promote new chemical reactivity.
If time allows, I will also talk about photochemical pumping with Carbon Nitride nanostructures and how that adds an engineering component to photoenergy conversions.
