An iron oxychloride (FeOCl) catalyst was developed for oxidative degradation of persistent organic compounds in aqueous solutions. Exceptionally high activity for the production of hydroxyl radical (OH·) by H2O2 decomposition was achieved, being 2-4 orders of magnitudes greater than that over other Fe-based heterogeneous catalysts. The relationship of catalyst structure and performance has been established by using multitechniques, such as XRD, HRTEM, and EPR. The unique structural configuration of iron atoms and the reducible electronic properties of FeOCl are responsible for the excellent activity. This study paves the way toward the rational design of relevant catalysts for applications, such as wastewater treatment, soil remediation, and other emerging environmental problems.

Urea electrolysis is ap rospective technology for simultaneous H 2 production and nitrogen suppression in the process of water being used for energy production. Its sustainability is currently founded on innocuous N 2 products; however,w ed iscovered that prevalent nickel-based catalysts could generally over-oxidizeu rea into NO 2 À products with % 80 %F aradaic efficiencies,p osing potential secondary hazards to the environment. Trace amounts of over-oxidized NO 3À and N 2 Owere also detected. Using 15 Nisotopes and urea analogues,w ed erived an itrogen-fate network involving aN O 2 À -formation pathwayv ia OH À -assisted C À Nc leavage and two N 2 -formation pathwaysv ia intra-and intermolecular coupling.D FT calculations confirmed that C À Nc leavage is energetically more favorable.I nspired by the mechanism, ap olyaniline-coating strategy was developed to locally enrich urea for increasing N 2 production by af actor of two.T hese findings provide complementary insights into the nitrogen fate in water-energy nexus systems.

NiFe oxyhydroxide is one of the most promising oxygen evolution reaction (OER) catalysts for renewable hydrogen production, and deciphering the identity and reactivity of the oxygen intermediates on its surface is a key challenge but is critical to understanding the OER mechanism as well as designing water-splitting catalysts with higher efficiencies. Here, we screened and utilized in situ reactive probes that can selectively target specific oxygen intermediates with high rates to investigate the OER intermediates and pathway on NiFe oxyhydroxide. Most importantly, the oxygen atom transfer (OAT) probes (e.g. 4-(Diphenylphosphino) benzoic acid) could efficiently inhibit the OER kinetics by scavenging the OER intermediates, exhibiting lower OER currents, larger Tafel slopes and larger kinetic isotope effect values, while probes with other reactivities demonstrated much smaller effects. Combining the OAT reactivity with electrochemical kinetic and operando Raman spectroscopic techniques, we identified a resting Fe=O intermediate in the Ni-O scaffold and a rate-limiting O-O chemical coupling step between a Fe=O moiety and a vicinal bridging O. DFT calculation further revealed a longer Fe=O bond formed on the surface and a large kinetic energy barrier of the O-O chemical step, corroborating the experimental results. These results point to a new direction of liberating lattice O and expediting O-O coupling for optimizing NiFe-based OER electrocatalyst.