This review summarizes some representative advances in PCMs with electrochemical applications in the past ten years, expecting to provide some useful guidance for future research.

Triiodide/iodide (I3 –/I–) represents a widely used redox couple and plays an important role in some photovoltaic devices. However, the understanding of the triiodide reduction kinetics occurring at the liquid/electrode interface is very limiting, which largely hinders the identification of highly efficient electrode material. In this work, by virtue of DFT calculations, we systematically investigated the I3 – electroreduction at some acetonitrile/electrode interfaces and uncovered two new BEP relations for the key elementary steps, I2 dissociation and I* desorption through one-electron reduction. Furthermore, by utilizing a steady-state microkinetic model, we successfully identified a general volcano-shaped activity trend of triiodide electroreduction as a function of a single descriptor, the adsorption energy of I atom (E ad I) at the interface. Our results show that a good catalyst should possess an E ad I within the range of 0.3–0.6 eV, while the optimal E ad I is 0.43 eV, where the surface coverages of free sites and iodine atoms are equal. In particular, the dependences of the volcano shape on the electrochemical conditions (external voltage, temperature, concentration, and transfer coefficient) are quantitatively discussed. Some suggestions for the optimization of experimental conditions and design of better catalysts are also provided.

Sludge-based biochar was able to catalyse persulfate decomposition to produce singlet oxygen for pollutant degradation.

Production of hydrogen peroxide (H 2 O 2 ) via in situ electrochemical water oxidation possesses great potential applications in the energy and environment fields. In this work, for the first time, we reported a C,N codoped TiO 2 electrode for selective electrocatalytic water oxidation to produce H 2 O 2 in an acidic electrolyte. An electrochemical anodic oxidation method combined with postcalcination in the presence of urea was applied to fabricate such a C,N codoped TiO 2 electrode, which was evidenced by detail structural characterizations. The calcination temperature and urea atmosphere were found to play key roles in its catalytic performances; the optimized 600N sample exhibited an onset potential of 2.66 V (vs Ag/AgCl) and a Tafel slope of 51 mV dec −1 at pH 3. Under the optimal applied potential, the cumulative H 2 O 2 concentration for this sample reached 0.29 μmol L −1 cm −2 h −1 . More importantly, a simple recalcination strategy was developed to recover the deactivation electrode. This study proposed an efficient C,N codoped TiO 2 electrode toward water oxidation to selectively produce H 2 O 2 in the acidic electrolyte, which could be further used to in situ generate H 2 O 2 for the energy-and environment-related fields with water as the precursor.