Electrochemically Oxidized Aligned Carbon Nanotube Arrays Embedding Foam Substrates for Water Splitting

Designing highly active electrocatalysts for both hydrogen and oxygen evolution with good durability at large current densities is very significant for water splitting. In this study, a new type of catalytic electrode was developed for water splitting. This electrode was made by growing microflower-like NiFeP on an aligned carbon nanotube (CNT) array network skeleton that was embedded in a Ni foam (NF) substrate. This design is aimed at enhancing the electrocatalytic activity for both hydrogen and oxygen evolution. The results showed that the resulting electrode (ECO-NF-ACNT@NiFeP) had a porous structure and was hydrophilic and highly resistant to corrosion, leading to improved activity for both the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). The overpotential for harvesting a 10 mA cm^–2 OER and HER current density was 97 and 190 mV, respectively, and the overpotential for reaching 100 mA cm^–2 was 345 and 348 mV, respectively. These results are significantly better than those of commercial RuO₂ and Pt/C catalysts and provide a promising direction for developing water splitting catalysts.