Will Any Crap We Put into Graphene Increase Its Electrocatalytic Effect?
https://doi.org/10.1021/acsnano.9b00184
The doping of graphene with a plethora of elements has been reported as enhancing its electrocatalytic performance. It has become almost a paradigm that the once fantastic graphene for electrocatalysis is not so fantastic anymore and that we need to add something to it (i.e., a dopant) to make it great again...
After doping with individual atoms, it was apparently again not enough for electrocatalysis (one may be surprised that there is always room for improvement) and two-element-doped graphene was claimed to be a better catalyst than graphene doped with one element due to a so-called "synergistic effect". Multielemental (i.e., three or more "heteroatoms" other than carbon) doped graphene became a trend.( It seems that whatever "crap" we put into graphene, electrocatalysis increases.
We demonstrate in the following text the meaninglessness of the never-ending co-doping of graphene. We decided to follow the hyperbole of ever multiplying dopants; however, instead of using expensive and toxic chemicals such as ammonia, fluorine, chlorine, boranes, etc., we took a page from the pre-Haber-Bosch era and sought natural materials for the fertilization of graphene and used guano as a dopant.
In summary, we demonstrated that bird dropping-treated graphenes indeed make graphene more electrocatalytic than nondoped graphene. Both bird-dropping-decorated graphenes and control nondoped graphenes show the same morphology. Graphenes decorated with bird droppings contain additional N, S, and P in the material. These decorated graphenes exhibit much better electrocatalytic properties toward both oxygen reduction and hydrogen evolution, and, in this case, it can be considered as a potential multifunctional catalyst for both ORR (oxygen reduction reaction) and HER (hydrogen evolution reactions). Because doping graphene with cheap bird droppings produces more electrocatalytic materials than many complex multielemental doping procedures, we do not see any justification for such efforts, and we believe that researchers should focus their energy on other research directions. To conclude in a positive (and a bit satiric) tone, we speculate that the chemical composition of chicken guano can be tailored by feedstock (chick feed), and, therefore, the quality of the resulting doped catalyst can be further improved. We believe that there is potential for the bird dropping-doped graphene for fuel cells and in a hydrogen economy, and we believe that bird droppings can become a high-value-added product such as guano was in the past. One can only hope that with such dramatic advantages, no wars (even trade wars) will be started over bird droppings this time.
