Novel copper oxides oxygen evolving catalyst in situ for electrocatalytic water splitting

Recent Advances in the Development of Water Oxidation Electrocatalysts at Mild pH

Developing anodic oxygen evolution reaction (OER) electrocatalysts with high catalytic activities is of great importance for effective water splitting. Compared with the water-oxidation electrocatalysts that are commonly utilized in alkaline conditions, the ones operating efficiently under neutral or near neutral conditions are more environmentally friendly with less corrosion issues. This review starts with a brief introduction of OER, the importance of OER in mild-pH media, as well as the fundamentals and performance parameters of OER electrocatalysts. Then, recent progress of the rational design of electrocatalysts for OER in mild-pH conditions is discussed. The chemical structures or components, synthetic approaches, and catalytic performances of the OER catalysts will be reviewed. Some interesting insights into the catalytic mechanism are also included and discussed. It concludes with a brief outlook on the possible remaining challenges and future trends of neutral or near-neutral OER electrocatalysts. It hopefully provides the readers with a distinct perspective of the history, present, and future of OER electrocatalysts at mild conditions.

An amorphous FeNiOx thin film obtained by anodic electrodeposition as an electrocatalyst toward the oxygen evolution reaction

Novelty of the work: amorphous FeNiO_x was fabricated via anodic electrochemical deposition as an efficient catalyst for OER.

Encapsulation of Ni/Fe3O4 heterostructures inside onion-like N-doped carbon nanorods enables synergistic electrocatalysis for water oxidation

The rational modulation of composition and structure is critical for the development of robust and efficient oxygen evolution reaction (OER) catalysts for water splitting. In this study, an onion-like N-doped carbon nanorods hybrid (denoted as ONC) with encapsulated Ni/Fe₃O₄ heterostructures has been fabricated by the pyrolysis of an NiFe-based coordination polymer under a N₂ atmosphere. The nanorod-like morphology is transferred from the polymer to the hybrids and generates ONC nanolayers encapsulated with core-shell Ni/Fe₃O₄ nanostructures. The synergistic effects between the ONC layers and the encapsulated Ni/Fe₃O₄ heterostructures result in high electronic conductivity due to the nitrogen-doped carbon with an appropriate level of defects and enlarged electrochemical surface area due to the well-defined mesoporous morphology. Compared with Ni@ONC, Fe₃O₄@ONC, NiFe₂O₄ and commercial RuO₂ electrocatalysts, the as-prepared Ni/Fe₃O₄@ONC exhibits extraordinary electrocatalytic activity for water oxidation with an overpotential of merely 296 mV at 10 mA cm^-2 and a small Tafel slope of 61 mV dec^-1. This Ni/Fe₃O₄@ONC OER catalyst highlights the great potential of integrating hetero-composite nanocatalysts with hetero-atom doped nanocarbon supports for the development of high-performance electrocatalysts for renewable energy applications.