Recent studies have shown that the lack of ideal anodes with both good activity and stability is still one of the critical problems in electrochemical oxidation for organic wastewater treatment. The electrochemical properties, the activity and stability for anodic oxidation of various phenolic compounds, and the degradation mechanism on a novel β-PbO 2 electrode modified with fluorine resin were investigated. The anode life after modification was greatly improved to be more than 10 yr in common electrochemical current conditions. Such an anode was effective for partial degradation of phenolic compounds, but selective because reactive activities were varied with different substituents. Characterized by SEM and XRD, the crystal form of the anode was verified to be mainly β-PbO 2 , and it hardly changed when used for p-nitrophenol degradation for around 320 h although there existed slow electrode corrosion. The active species generated during anodic oxidation were determined to be mainly hydroxyl radical and little ozone. The reactions between hydroxyl radical and phenolic compounds were proved to be electrophilic reactions, based on which a general electrochemical degradation mechanism for aromatic compounds was proposed. In general, such a novel anode has a good performance for organics degradation with perfect electrode life, showing potential for environmental application.

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Fresh and arsenic-poisoned V2O5–WO3/TiO2 catalysts are investigated by experiments and DFT calculations for SCR activity and the deactivation mechanism. Poisoned catalyst (1.40% of arsenic) presents lower NO conversion and more N2O formation than fresh. Stream (5%) could further decrease the activity of poisoned catalyst above 350 °C. The deactivation is not attributed to the loss of surface area or phase transformation of TiO2 at a certain arsenic content, but due to the coverage of the V2O5 cluster and the decrease in the surface acidity: the number of Lewis acid sites and the stability of Brønsted acid sites. Large amounts of surface hydroxyl induced by H2O molecules provide more unreactive As–OH groups and give rise to a further decrease in the SCR activity. N2O is mainly from NH3 unselective oxidation at high temperatures since the reducibility of catalysts and the number of surface-active oxygens are improved by As2O5. Finally, the reaction pathway seems unchanged after poisoning: NH3 adsorbed on both Lewis and Brønsted acid sites is reactive.

Developing noble metal-free electrocatalysts toward hydrogen evolution reaction (HER) that can work well at ultrahigh current density are crucial components in renewable energy technologies. Herein, we have reported a strongly coupled 3D hybrid electrocatalyst, which consists of N-doped MoO 2 with Ni 3 S 2 grown on Ni foam (N-MoO 2 /Ni 3 S 2 NF) through an annealing treatment, followed by a thermal ammonia reaction. This N-MoO 2 /Ni 3 S 2 with a particle size of ∼50 nm was evenly grown on the Ni substrate in this 3D hybrid system. Benefiting from the strong coupling effect, the N-MoO 2 /Ni 3 S 2 NF exhibited a high HER performance in basic media, with a small value of the Tafel slope (76 mV dec −1 ) and a low potential of 517 mV at 1000 mA cm −2 , which was superior to that of Pt/C (631 mV at 1000 mA cm −2 ). Experimental results revealed that constructing a coupling interface between N-MoO 2 and Ni 3 S 2 facilitated the absorption and dissociation of water molecules, consequently boosting the HER activity. Additionally, the 3D N-MoO 2 /Ni 3 S 2 NF hybrid could act as a bifunctional electrode for both anode (biomass upgrading) and cathode (HER), which only required a lower potential of 2.08 V at 100 mA cm −2 as compared to the overall water splitting (2.25 V) and achieved a high biomass conversion ratio of over 90%. Moreover, substituting oxygen evolution reaction by urea oxidation reaction also can assist energy-saving hydrogen evolution for 3D N-MoO 2 /Ni 3 S 2 NF.

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Sluggish water dissociation kinetics in theVolmer step on platinum-free electrocatalysts limits the development of hydrogen evolution from economical water-alkali electrolyser. Herein, an unusual nanosheets electrocatalyst of molybdenum-doped cobalt selenide with selenium vacancy encapsulated within N-doped carbon matrix (Mo-Co 0.85 Se VSe /NC) for efficient hydrogen evolution reaction (HER) is reported. Benefiting from the optimized electronic structure, this Mo-Co 0.85 Se VSe /NC nanosheet exhibits a high catalytic activity for alkaline HER, achieving the current densities of 10 and 200 mA cm −2 at low overpotentials of 151 and 275 mV, respectively. These results are among the highest catalytic activities in respect with all previously reported transition-metal-selenide based HER electrocatalysts. The combined in situ spectroscopic and theoretical studies reveal that the incorporation of Modopant and Se vacancies into Co 0.85 Se efficiently enhances electron transfer from Mo to Co atom through the bridging Se atom, leading to the formation of enriched electronic Co site to accelerate water dissociation, eventually facilitating the overall alkaline HER process. An integrated Zn-H 2 O battery with a Mo-Co 0.85 Se VSe /NC cathode is developed to further demonstrate the potential applications of the newly developed HER catalyst.