Polyethylene terephthalate (PET) is the most used polymer, but its natural degradation kinetics is sluggish; therefore, its disposal poses an environmental threat. Here, we demonstrate electrocatalytic PET upcycling with full recyclability with a cobalt containing one-dimensional (1D) coordination polymer as an electrocatalyst that can operate at a low onset potential of 1.27 V vs. RHE, affording terephthalic acid (TPA) in 100% yield and potassium diformate (KDF) with ∼80% selectivity as isolated products, along with the coproduction of hydrogen. The mechanistic analysis, as obtained from systematic studies with PET, its oligomer, and monomer revealed a pathway for a side reaction generating carbonate (CO3 2–) that follows a formate oxidation instead of an oxalate oxidation pathway. The catalytic performance and the mechanistic insight gained from the study, are useful in developing the PET upcycling technologies with maximized formate/KDF production.

Electrocatalytic water splitting to hydrogen (H2) is an ideal approach to generate renewable energy. One of the major drawbacks is the tightly coupled kinetically sluggish and energy inefficient anodic oxygen evolution reaction (OER) with hydrogen forming a cathodic half-cell reaction which leads to a significant reduction in overall cell efficiency. In this context, before reviewing the literature, we have first briefly analyzed the energetics of overall water splitting, problems, and challenges under different pH conditions which can be useful for the further understanding of the process. Replacement of the anodic OER by a thermodynamically favorable substrate oxidation offers flexibility, value addition, and energy efficiency in the case of hybrid or assisted water electrolysis to afford hydrogen. Recent progress in terms of sacrificial oxidants in hybrid water electrolysis are discussed in this context, where the sacrificial oxidants are so chosen that the oxidation often leads to its value addition. Also here, we have offered insights into interface designing in heterostructures by modulating chemical and electronic environments for the enhancement of the intrinsic catalytic activity and stability. The effect of incorporation of such materials into the overall water splitting reaction, their catalytic active sites, and interactions with intermediates are thoroughly explored. This review can be a good complement for better understanding of the elucidation of the interface role in hybrid water electrolysis for future commercial applications.

Catalyst development for water splitting to afford hydrogen as a green source of energy is one of the major areas of research in the pursuit of sustainable energy technology solution. Herein, the electrocatalytic water oxidation behaviour of two different Co‐pdc (H2pdc=pyridine‐2,5‐dicarboxylic acid) based metal‐organic frameworks (MOFs) of different dimensionalities (2D and 1D) is reported. 2D‐MOF {[Co(pdc)(H2O)2] ⋅ H2O}n acts as the mother which transforms into daughter 1D‐MOF {[Co(pdc)(H2O)2] ⋅ 7H2O}n via consecutive dehydration and rehydration. Within 2D‐MOF, the Co2+ shows six coordinated octahedral geometry with two coordinated water molecules and for the 1D‐MOF, Co2+ shows five coordinated square pyramidal geometry having two coordinated water molecules and one open metal site. Both the MOFs show excellent stability over a pH range of 3 to 11 even after 24 hours and show OER activity from neutral to alkaline medium. The MOFs retain their crystalline structure even after OER at neutral pH but eventually gets decomposed; but they are converted into their (oxy)hydroxides at pH 14. Interestingly, 1D MOF shows superior activity in both neutral and alkaline medium over the 2D framework for OER due to presence of open metal sites, better electrical conductivity and larger electrochemically active surface area.