NiFe Layered Double Hydroxide (LDH) Nanosheet Catalysts with Fe as Electron Transfer Mediator for Enhanced Persulfate Activation.

A highly efficient, durable, and cost-effective Fenton-like catalyst is desired to produce the sulfate radicals (•SO4-) for energy and environmental applications. The M(n+1)+/Mn+ redox cycle in metal catalysts requires a high redox potential for •SO4- generation. NiFe layered double hydroxide (LDH) nanosheets with a suitable redox potential for persulfate (PDS) activation were prepared via incorporating Fe into the Ni based LDH. With the help of Fe, the charge-transfer kinetics for the reduction of Ni3+ to Ni2+ was improved and the formation of unwanted Ni component with higher oxidation state was suppressed. The incorporated Fe as the electron transfer mediator enhanced the process of Ni(OH)2/NiOOH redox cycle. Therefore, NiFe LDH exhibited superior performance in PDS activation with exceptionally high activity for the phenolic compounds' degradation in neutral and basic conditions. This work is expected to inspire the rational design of LDHs based catalysts for PDS activation.