A schematic presentation for the unexpected blue-shifted luminescence of Eu²⁺ in M₅(Si₃O₉)₂ (M = Sr, Ba, Y, Eu, Mn) based on the preferential occupancy at the designated cation sites.

A schematic presentation for the valence transition from 3+ to 2+ of Eu in Ca _2(1+x) La _8(1−x) (SiO ₄ ) _6−x (PO ₄ ) _x O ₂ :Eu (0 ≤ x ≤ 6) based on the XANES spectroscopy analysis.

The coupling of the carbon dioxide reduction reaction (CO₂RR) and methanol oxidation reaction (MOR) holds great promise for the energy‐efficient production of HCOO⁻. However, anode catalysts' limited selectivity (<80%) and stability (<15 h) have impeded electron utilization and HCOO⁻ production rates. To overcome it, copper‐copper(I) oxide‐copper(II) oxide nanowires (Cu─CuO─Cu₂O NWs) catalysts have been developed, which exhibit exceptional performance in promoting the MOR with a faradic efficiency of nearly 100% at commercially viable current densities, and long stability over 100 h at 100 mA cm⁻². Interestingly, the unique structure of the catalysts, when exposed to methanol, facilitates a transition from Cu/CuO to Cu₂O. This phenomenon promotes the MOR while inhibiting the competitive oxygen evolution reaction (OER). By coupling the anodic reaction with cathodic CO₂ reduction, the system demonstrates exceptional performance in HCOO⁻ production, achieving an overall faradic efficiency of nearly 200% at 100 mA cm⁻² with a low cell voltage of 2.382 V. Techno‐economic analysis indicates that the production costs of HCOOH are ≈US$0.37 and 0.35 kg⁻¹ at 100 and 150 mA cm⁻², respectively, significantly lower than those associated with traditional electrochemical methods.