Three-dimensional Nanoporous Cu-Doped Ni Coating as Bifunctional Electrocatalyst for Hydrazine Sensing and Hydrogen Evolution Reaction.

Developing a cost-effective and efficient bifunctional electrocatalyst with simple synthesis strategy for hydrazine sensing and H evolution reaction (HER) is of utmost importance. Herein, a three-dimensional porous Cu-doped metallic Ni coating on Ti mesh (Ni(Cu) coating/TM) was successfully electrodeposited by a facile electrochemical method. Electrochemical etching of the electrodeposited Ni(Cu) coating with metallic Ni and Cu mixed phase on a Ti mesh contributed to the formation of a three-dimensional porous Cu-doped metallic Ni coating. Owing to the large specific surface area and enhanced electroconductivity caused by the porous structure and Cu doping, respectively, the developed Ni(Cu) coating/TM exhibited superior hydrazine sensing performance and electrocatalytic activity toward hydrogen evolution reaction (HER). The Ni(Cu) coating/TM electrode presented a good sensitivity of 3909µA mM-1cm-2and two relatively broad linear ranges from 0.004 mM to 2.915 mM and from 2.915 mM to 5.691 mM as well as a low detection limit of 1.90µM. In addition, the Ni(Cu) coating/TM required a relatively low HER overpotential of 140 mV to reach -10 mA cm-2and exhibited robust durability in alkaline solution. The excellent hydrazine electrooxidation and HER performance guarantee its promising application in hydrazine detection and energy conversion.

Performance and mechanism of FeS2/FeSxOy as highly effective Fenton-like catalyst for phenol degradation.

Developing a highly efficient Fenton-like catalyst working in a wide pH range is imperative to accomplish its practical wastewater treatment. Herein, FeS2/FeSxOy catalyst was synthesized by hydrothermal-solvothermal vulcanization with thioacetamide as a sulfur source. Characterization results confirmed FeS2/FeSxOy consisted of pyrite, kornelite, and szomolnokite. FeS2/FeSxOy exhibited superior catalytic activity toward H2O2 activation with more than 96% phenol removal within 5 min in pH 3.0 ∼ 8.0 at 30°C. Radical scavenging experiment and EPR analysis revealed both hydroxyl radicals (·OH) and superoxide anion radicals (O2·-) anticipated in phenol elimination, but ·OH played a dominant role. The detailed degradation experiments and density functional theory (DFT) calculation confirmed the vital role of FeS2 in enhancing phenol abatement. This study not only developed a highly active catalyst for H2O2 activation but also theoretically analyzed the FeS2 function in depth, which provided a guide for designing a highly efficient Fenton-like catalyst.