Tuning of Reciprocal Carbon-Electrode Properties for an Optimized Hydrogen Evolution.

Closing the material cycle for harmful and rare resources is a key criterion for sustainable and green energy systems. The concept of using scalable biomass-derived carbon electrodes to produce hydrogen from water was proposed here, satisfying the need for sustainability in the field of chemical energy conversion. The carbon electrodes exhibited not only water oxidation activity but also a strong self-oxidation when being used as anode for water splitting. The carbon oxidation, which is more energy-favorable, was intentionally allowed to occur for an improvement of the total current, thus enhancing the hydrogen production on the cathode side. By introducing different earth-abundant metals, the electrode could be well adjusted to achieve an optimized water/carbon oxidation ratio and an appreciable reactivity for practical applications. This promising methodology may become a very large driver for carbon chemistry when waste organic materials or biomass can be converted using its intrinsic energy content of carbon. Such a process could open a safe path for sub-zero CO2 emission control. The concept of how and which parameter of a carbon-based electrode can be optimized was presented and discussed in this paper.