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Abstract In this report, we elucidated the hydrogen evolution reaction (HER) catalytic activity of different metal-azaphthalocyanine unimolecular layer (AZUL) catalysts and compared the overpotentials in alkaline electrolyte membrane water electrolysis (AEMWE). While the overpotentials are bit higher compared to Pt/C, the system utilizing the FeAzPc-4N with Sustainion® showed a low overpotential of 2.02 V at 1.0 A/cm2 and faraday efficiency of 96.3% even among the previous alternative catalysts. It is noteworthy that the AZUL catalysts are not using precious metals and even comparing with other transition metal electrocatalysts, metal atom usage is much lower because only the single transition metal atom in the azapthalocyanine macrocycle works as a catalytic site.

The oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are important processes for various energy devices, including polymer electrolyte fuel cells, rechargeable metal–air batteries, and water electrolyzers. We herein report the preparation of a rare metal-free and highly efficient ORR/OER electrocatalyst by calcination of a mixture of blood meal and ascidian-derived cellulose nanofibers. The obtained carbon alloys showed high ORR/OER performances and proved to be promising electrocatalysts. The carbon alloys synthesized entirely from biomass resources not only lead to a new electrocatalyst fabrication process but also contribute to CO2 reduction and the realization of a good life-cycle assessment value in fabrication of a sustainable energy device.

Zn–air batteries have only been used in limited applications, such as hearing aid batteries, due to their low power density and standard voltage of around 1.4 V. Therefore, to use Zn–air batteries as a drive power source in cutting-edge devices such as drones, it is essential to improve the drive voltage and output power density. Here, we propose Zn–air batteries with a high potential (∼2.25 V) and high power density (∼318 mW/cm2) by using the newly designed iron azaphthalocyanine unimolecular layer (AZUL) electrocatalyst and a tandem Zn–air battery cell. The AZUL electrocatalyst in this new type of cell had a high electrochemical stability and high oxygen reduction reaction performance in the ultralow pH region, in which Pt and other metallic and inorganic electrocatalysts cannot be used. Furthermore, the tandem-electrolyte cells had a cell voltage of over 1.0 V at a high discharge current density of 200 mA/cm2, and the output power density was 1139 mWh/g(Zn) at 100 mA/cm2 discharge.

As part of ongoing efforts to realize a low‐carbon and hydrogen‐based society, there is an increasing demand for high‐performance electrocatalysts, which are key materials for fuel cells and water electrolysis systems. Although platinum group metals exhibit high catalytic activity, increasing production costs due to resource constraints, limited countries of production, and geopolitical supply issues are threatening their use. Therefore, it is crucial to make substantial changes in resource utilization for the sustainable production of electrochemical catalysts. Herein, the preparation of trifunctional biomass‐derived electrocatalysts for the oxygen reduction reaction and oxygen/hydrogen evolution reactions by the pyrolysis of cellulose nanofibers from ascidian tunicates, dried blood meal, and cyanocobalamin is reported. The combination of N, P, FeN4, and CoN4 structures incorporated in the carbon network leads to high electrochemical performance comparable with rare‐metal‐based electrocatalysts and other carbon alloy electrocatalysts. This work provides a possible strategy for fabricating high‐capacity energy storage devices from biomass resources such as industrial waste without the need for rare metals or other harmful heavy metals.