Materials. Alkali lignin (AL), tannic acid (TA), carbon nanopowder <100 nm particle size (CAS 7440-44-0) and Nafion perfluorinated resin solution (5 wt. % in a mixture of lower aliphatic alcohols and water) were obtained from Sigma-Aldrich. 20 wt.% Pt/C was purchased from the Fuel Cell Store. Urea, NaOH, KOH, ethanol, and isopropyl alcohol (IPA) were obtained from ECP chemicals, New Zealand. All the reagents were of analytical grade and used as received without further purification. Deionised water (Milli-Q, resistivity 18.2 MΩ•cm) was used throughout the synthesis and experimental processes. Bovine blood was procured from Auckland meat processors to extract haemoglobin (Hb).