pmda

Layered double hydroxides (LDHs) are a family of high-profile layer materials with tunable metal species and interlayer spacing, and herein the LDHs are first investigated as bifunctional electrocatalysts. It is found that trinary LDH containing nickel, cobalt, and iron (NiCoFe-LDH) shows a reasonable bifunctional performance, while exploiting a preoxidation treatment can significantly enhance both oxygen reduction reaction and oxygen evolution reaction activity. This phenomenon is attributed to the partial conversion of Co²⁺ to Co³⁺ state in the preoxidation step, which stimulates the charge transfer to the catalyst surface. The practical application of the optimized material is demonstrated with a small potential hysteresis (800 mV for a reversible current density of 20 mA cm⁻²) as well as a high stability, exceeding the performances of noble metal catalysts (commercial Pt/C and Ir/C). The combination of the electrochemical metrics and the facile and cost-effective synthesis endows the trinary LDH as a promising bifunctional catalyst for a variety of applications, such as next-generation regenerative fuel cells or metal–air batteries.

It is found that incorporating Co into NiFe-layered double hydroxides (LDHs) can significantly improve the oxygen reduction reaction (ORR) activity and both the ORR and oxygen evolution reaction activities of trinary NiCoFe-LDHs can be significantly improved by a preoxidation process. This improvement is attributed to the formation of Co³⁺ in the intralayer, and results in the conductivity improvement of the material.

A single pot electrolytic synthesis of hydrogen and carbon fuels is achieved through the use of a mixed, hydroxide/carbonate electrolyte, a nickel anode (generating O₂), and a nickel or steel cathode. In article number 1401791 Stuart Licht and co-workers report that the generation of hydrogen and carbon fuels is driven with conventional power or efficiently generated from sunlight using solar thermal and electric (CPV) energy as STEP (solar thermal electrochemical process) fuels.

Surface phosphate groups facilitate solar water oxidation on the surface of iron oxide thin films, even in a neutral electrolyte. The method reported by Jae Sung Lee and co-workers in article number 1400476 provides an effective path to the stability engineering of photoelectrodes to employ any electrolyte of choice. Such stability engineering is a critical issue in solution-based energy devices based on hybrid materials with different stability characteristics.

Instead of conventional semiconductor photoelectrodes, herein, we focus on BiFeO₃ ferroelectric photoelectrodes to break the limits imposed by common semiconductors. As a result of their prominent ferroelectric properties, the photoelectrodes are able to tune the transfer of photo-excited charges generated either in BiFeO₃ or the surface modifiers by manipulating the poling conditions of the ferroelectric domains. At 0 V vs Ag/AgCl, the photocurrent could be switched from 0 μA cm⁻² to 10 μA cm⁻² and the open-circuit potential changes from 33 mV to 440 mV, when the poling bias of pretreatment is manipulated from −8 V to +8 V. Additionally, the pronounced photocurrent from charge injection of the excited surface modifiers could be quenched by switching the poling bias from +8 V to −8 V.

Poling station: The orientation of the BiFeO₃ (BFO) band bending at the BFO/electrolyte in polycrystalline BFO photoelectrodes can be switched from upwards to downwards by poling pretreatments of +8 V or −8 V, respectively. It is thus possible to manipulate photoelectrochemical reactions on a single ferroelectric photoelectrode.

A plasmon-induced water splitting system that operates under irradiation by visible light is described by H. Misawa et al. in their Communication on page 10350 ff. The system uses both sides of the same strontium titanate single-crystal substrate to separate hydrogen and oxygen. The chemical bias is substantially reduced by plasmonic effects because of efficient water oxidation.