A Cobalt-Based Film for Highly Efficient Electrocatalytic Water Oxidation in Neutral Aqueous Solution

Strategies to Develop Earth-Abundant Heterogeneous Oxygen Evolution Reaction Catalysts for pH-Neutral or pH-Near-Neutral Electrolytes

The anodic oxygen evolution reaction (OER) is the bottleneck of water splitting to produce hydrogen due to its sluggish kinetics. In order to lower the energy cost, highly active and cost-efficient OER catalysts need to be used to overcome the OER reaction barrier, especially in neutral pH. Compared to alkaline or acidic electrolytes, pH-neutral or pH-near-neutral electrolytes are considered to be cheaper and safer, and water from rivers and the sea could be used directly under such conditions. However, OER under neutral pH is challenging compared to the OER catalysts for alkaline conditions. Therefore, OER catalysts for neutral or near-neutral pH have not been pursued significantly and, hence, there are limited advances in this area. Here, the progress made in the research and development of earth-abundant heterogeneous catalysts for OER in three pH-neutral or pH-near-neutral systems, namely, the phosphate system, the carbonate system, and the borate system, are systematically reviewed and summarized for the first time. Strategies to develop high-performance OER catalysts for neutral pH are reviewed and summarized. In addition, future challenges and opportunities in this field are discussed, which may shed some light on the future developments of earth-abundant heterogeneous catalysts for OER in neutral or near-neutral pH.

Nickel oxide–polypyrrole nanocomposite electrode materials for electrocatalytic water oxidation

Electrochemically prepared nickel oxide nanoparticles entrapped into a polymer matrix as efficient material for O₂ evolution.

Highly Active Three-Dimensional NiFe/Cu2 O Nanowires/Cu Foam Electrode for Water Oxidation

Water splitting is of paramount importance for exploiting renewable energy-conversion and -storage systems, but is greatly hindered by the kinetically sluggish oxygen evolution reaction (OER). In this work, a three-dimensional, highly efficient, and durable NiFe/Cu₂ O nanowires/Cu foam anode (NiFe/Cu₂ O NWs/CF) for water oxidation in 1.0 m KOH was developed. The obtained electrode exhibited a current density of 10 mA cm^-2 at a uniquely low overpotential of η=215 mV. The average specific current density (j_s ) was estimated, on the basis of the electrocatalytically active surface area, to be 0.163 mA cm^-2 at η=310 mV. The electrode also displayed a low Tafel slope of 42 mV decade^-1 . Moreover, the NiFe/Cu₂ O NWs/CF electrode could maintain a steady current density of 100 mA cm^-2 for 50 h at an overpotential of η=260 mV. The outstanding electrochemical performance of the electrode for the OER was attributed to the high conductivity of the Cu foam and the specific structure of the electrode with a large interfacial area.

A new preparation of a bifunctional crystalline heterogeneous copper electrocatalyst by electrodeposition using a Robson-type macrocyclic dinuclear copper complex for efficient hydrogen and oxygen evolution from water

Electro-deposited Cu(OH)₂/Cu₂O-based thin film on FTO with the macrocyclic dicopper complex shows excellent water splitting activity in excellent Faradaic efficiency.

Enhanced durability of an iridium-bipyridine complex embedded into organosilica nanotubes for water oxidation

Robust bipyridine-incorporated organosilica nanotubes were used to fabricate heterogeneous iridium-bipyridine catalysts, which showed enhanced durability in the water oxidation reaction, benefiting from the stable nanotube structures as well as the isolated active sites.