So dug around on this a bit. The paper is well written and fairly straight forward. I don't know a whole lot about the inorganic chem field so the methods section is going to take some time, but the technological side makes sense. Essentially the author argues that energy storage is too costly. Why lug a bunch of batteries around when all you need to do is convert a readily available resource to a high energy state. The author also shows a 200X efficiency improvement. I expect to see another paper out of this lab soon after they make an engineering prototype.
This paragraph describes the chemistry
The Co-based oxygen evolving catalysts form as thin ﬁlms on conducting surfaces when aqueous solutions of Co 2+ salts are electrolyzed in the presence of phosphate (Coâ€“Pi) or borate (Coâ€“Bi);4,5 a similar strategy was used to create a Niâ€“Bi catalyst. 6 These catalysts are of interest because they: (1) form in situ under mild conditions on a variety of conductive substrates, 4â€“6 (2) exhibit high activity in pH 7â€“9 water at room temperature, 4,5 (3) are functional in salt water, 5 (4) are comprised of inexpensive, earth-abundant materials, 4,5 (5) self-heal by reversing catalyst corrosion at open circuit upon re-application of an anodic potential, 18 (6) can be interfaced with light absorbing and charge separating materials to enhance photoelectrochemical water splitting, 19â€“21 and (7) are functional models of the oxygenevolving complex of Photosystem II. 22 The simple operation of the catalyst from conventional water sources under benign conditions is an important step towards providing distributed
solar energy storage at low-cost with a fast transition to technology. 23
Here is the conclusion in its entirety, including the line that states a realized 200X increase in current density by using a 3D foam electrode.
Initial reports of the discovery and function of the Co-OEC catalyst were focused on deﬁning the science of the catalyst, not optimizing electrode performance. These reports show that the catalyst structure is composed of ordered units of molecular dimensions, 29,30 detail the nature of the active species 31 and shed insight on the mechanism of the oxygen evolving reaction. 32 We now show that the performance of electrodes functionalized with the catalyst, as quantiﬁed by water-oxidation current density at ﬁxed overpotential, can be increased by >200 while demonstrating exceptional operational stabilities simply by increasing the number of Co active sites with increased catalyst loading for a speciﬁc geometric electrode area and facilitating mass transport to and away from the electrode using a ﬂow cell conﬁguration. Additionally, operation at neutral and near neutral pHs may serve to reduce the formation of passivating oxide layers of indigenous metals commonly found in natural water supplies
(e.g., Ca(OH)2, Mg(OH)2, etc.) and inhibit denaturation of biomolecules. These processes are accelerated in caustic alkali and can lead to electrode deactivation. The ease of operation of anodes functionalized with the Co-OEC catalyst at appreciable geometric current density, together with its ability to be highly manufacturable, 33 to operate in natural water sources and to require only a simple pressure membrane bodes well for the translation of this catalyst to a viable technology.