The mechanism of high-transition-temperature (high-T(c)) superconductivity in doped copper oxides is an enduring problem. Antiferromagnetism is established as the competing order, but the relationship between the two states in the intervening 'pseudogap' regime has become a central puzzle. The role of the crystal lattice, which is important in conventional superconductors, also remains unclear. Here we report an anomalous increase of the distance between copper oxide planes on cooling, which results in negative thermal volume expansion, for layered ruthenium copper oxides that have been doped to the boundary of antiferromagnetism and superconductivity. We propose that a crossover between these states is driven by spin ordering in the ruthenium oxide layers, revealing a novel mechanism for negative lattice expansion in solids. The differences in volume and lattice strain between the distinct superconducting and antiferromagnetic states can account for the phase segregation phenomena found extensively in low-doped copper oxides, and show that Cooper pair formation is coupled to the lattice. Unusually large variations of resistivity with magnetic field are found in these ruthenium copper oxides at low temperatures through coupling between the ordered Ru and Cu spins.

Cation ordering in Ba3VWO8.5 disrupts long-range oxygen diffusivity parallel to the c-axis resulting in reduced ionic conductivity.

As a pure and sustainable source of power, hydrogen (H2) is the desired chemical candidate for the future energy mix. Water electrolysis has been regarded as an effective method for producing clean and ultrapure hydrogen gas. However, its large-scale applications are hampered by its slow kinetics, particularly due to its slow anodic half-reaction i.e., the oxygen evolution reaction (OER). Another strategy based on chemical-assisted electrocatalytic energy-saving hydrogen production has recently been developed with great potential to address barriers associated with OER. In this case, OER is replaced by organic oxidation reactions that are thermodynamically more favorable, which substantially reduces the voltage required for H2 evolution and also facilitates the co-production of organic value-added products. Oxidation of biomass derivatives, such as alcohols, is the most suitable strategy for producing value-added chemicals with energy-saving hydrogen production. This Review focuses on the characteristics of making electrolytic hydrogen production more cost-efficient by using different alcohols. We have reviewed the fundamentals and key parameters for alcohol-assisted electrochemical hydrogen production and discussed several anodic alcohol oxidation reactions with value-added products. The choice of electrocatalysts, strategies to increase the reaction selectivity, and the possible cell architectures are elaborated in detail.