Reinventing MoS2 Co-catalytic Fenton reaction:Oxygen-incorporation mediating surface superoxide radical generation

To better understand the mechanisms of hydrogen peroxide(H_(2)O_(2))’s decomposition and reactive oxygen species(ROS)’s formation on the catalyst’s surface is always a critical issue for the environmental application of Fenton/Fenton-like reaction.We here report a new approach to activate H_(2)O_(2) in a co-catalytic Fenton system with oxygen incorporated MoS2,namely MoS_(2−x) O_(x) nanosheets.The MoS_(2−x) O_(x) nanosheets assisted co-catalytic Fenton system exhibited superior degradation activity of emerging antibiotic contaminants(e.g.,sulfamethoxazole).Combining density functional theory(DFT)calculation and experimental investigation,we demonstrated that oxygen incorporation could improve the intrinsic conductivity of MoS_(2−x) O_(x) nanosheets and accelerate surface/interfacial charge transfer,which further leads to the efficacious activation of H_(2)O_(2).Moreover,by tuning the oxygen proportion in MoS_(2−x) O_(x) nanosheets,we are able to modulate the generation of ROS and further direct the oriented-conversion of H_(2)O_(2) to surface-bounded superoxide radical(·O_(2−surface)).It sheds light on the generation and transformation of ROS in the engineered system(e.g.,Fenton,Fenton-like reaction)for efficient degradation of persistent pollutants.

催化光度法测定人发中超痕量钴的研究

本文研究了氨水介质中钴(Ⅱ)催化过氧化氢氧化邻苯二酚紫褪色反应及其动力学条件,建立了测定超痕量钴(Ⅱ)的快速方法。测定钴(Ⅱ)的范围为0～40×1/25 ng/mL,方法灵敏度为1.2×10^(-12)g/mL,用以测定人发中的痕量钴(Ⅱ),获得了满意结果。

Hydrogenation/Dehydrogenation Performances of the MgH_2-WS_2 Composites

The hydrogenation/dehydrogenation kinetics and thermodynamic behaviors of the MgH2- WS2 composites were investigated. The TPD （Temperature-Programmed-Desorption） curves showed that the onset dehydrogenation temperature of the MgH2 ＋ 20wt% WS2 composite was 615 K, 58 K lower than that of the pristine MgH2. The kinetic measurements showed that within 21 rain, the MgH2 ＋ 20wt% WS2 composite could absorb 2.818wt% at 423 K, and release 4.244 wt% of hydrogen at 623 K, while the hydriding/ dehydriding capacity of MgH2 reached only 0.979wt% and 2.319wt% respectively under identical conditions. The improvement of hydrogenation/dehydrogenation performances for the composite was attributed to the co- catalytic effect between the new phases W and MgS which formed durin~ the ball-milliw, ~rocess.

Achieving integrated capture and reduction of CO_(2):A promising electrocatalyst

To realize the goal of carbon peaking and carbon neutrality,CO_(2) capture and utilization technology is becoming increasingly urgent.However,the low efficiency and complex processes limit its large-scale application.Among utilization technology of CO_(2),electrochemical CO_(2) reduction reaction(CO_(2)RR)has attracted interest,attributing to the use of clean energy and the final product of value-added fuels.The construction of catalysts with integrated CO_(2) capture and reduction ability is expected to bridge the gap between CO_(2) capture and conversion,achieving the direct utilization of flue gas,reducing costs,and simplifying devices.Keeping` this in mind,we give this review to introduce the problems of lowconcentration CO_(2)RR and the significance of coupled CO_(2) capture/conversion electrocatalysts in addressing the emission of industrial flue gas first.Then,the regulation strategies,including functional group modification,co-catalytic effect,and catalysts-impurities interaction,which affected the CO_(2) capture and electroreduction capacity towards catalysts were summarized and discussed.Finally,the challenges and perspectives about the design for linked CO_(2) capture/conversion processes were proposed.This review will provide new insight into the building of multifunctional catalysts for CO_(2) conversion.

Efficient Fe（Ⅲ）/Fe（Ⅱ） cycling triggered by MoO2 in Fenton reaction for the degradation of dye molecules and the reduction of Cr（Ⅵ）

There is a relatively low efficiency of Fe(Ⅲ)/Fe(Ⅱ) conversion cycle and H2 O2 decomposition(<30%) in conventional Fenton process,which further results in a low production efficiency of ·OH and seriously restricts the application of Fenton.Herein,we report that the commercial MoO2 can be used as the cocatalyst in Fenton process to dramatically accelerate the oxidation of Lissamine rhodamine B(L-RhB),where the efficiency of Fe(Ⅲ)/Fe(Ⅱ) cycling is greatly enhanced in the Fenton reaction meanwhile.And the L-RhB solution could be degraded nearly 100% in 1 min in the MoO2 cocatalytic Fenton system under the optimal reaction condition,which is apparently better than that of the conventional Fenton system(~50%).Different from the conventional Fenton reaction where the ’OH plays an important role in the oxidation process,it shows that 1 O2 contributes most in the MoO2 cocatalytic Fenton reaction.However,it is found that the exposed Mo^4+ active sites on the surface of MoO2 powders can greatly promote the rate-limiting step of Fe^3+/Fe^2+ cycle conversion,thus minimizing the dosage of H2 O2(0.400 mmol/L) and Fe^2+(0.105 mmol/L).Interestingly,the MoO2 cocatalytic Fenton system also exhibits a good ability for reducing Cr(Ⅵ) ions,where the reduction ability for Cr(Ⅵ) reaches almost 100% within 2 h.In short,this work shows a new discovery for M002 cocatalytic advanced oxidation processes(AOPs),which devotes a lot to the practical water remediation application.

"Small amount for multiple times" of H_(2)O_(2) feeding way in MoS_(2)-Fex heterogeneous fenton for enhancing sulfadiazine degradation

In recent years, MoS_(2) catalyzed/cocatalyzed Fenton/Fenton-like systems have attracted wide attention in the field of pollution control, but there are few studies on the effect of H_(2)O_(2) feeding way on the whole Fenton process. Here, we report a new type of composite catalyst (MoS_(2)-Fe_(x)) prepared in a simple way with highly dispersed iron to provide more active sites. MoS_(2)-Fe_(x) was proved to possess selectivity for singlet oxygen (^(1)O_(2)) in effectively degrading sulfadiazine with a wide pH adaptability (4.0~10.0). Importantly, the mechanism of the interaction between H_(2)O_(2) and MoS_(2) on the Fenton reaction activity was revealed through the combination of experiment and density functional theory (DFT) calculations. Compared to the traditional “a large amount for one time” feeding way of H_(2)O_(2), the “small amount for multiple times” of H_(2)O_(2) feeding way can increase the degradation rate of sulfadiazine from 36.9% to 91.1% in the MoS_(2)-Fe_(x) heterogeneous Fenton system. It is demonstrated that the “small amount for multiple times” of H_(2)O_(2) feeding way can reduce the side reaction of decomposition of H_(2)O_(2) by MoS_(2) and effectively improve the utilization rate of H_(2)O_(2) and the stability of MoS_(2)-Fe_(x). Compared with Fe_(2)O_(3)^(-)based Fenton system, MoS_(2)-Fe_(x) can significantly save the amount of H_(2)O_(2). Compared with nano-iron powder, the formation of iron sludge in MoS_(2)-Fe_(x) system was significantly reduced. Furthermore, long-term degradation test showed that the MoS_(2)-Fe75/H_(2)O_(2) system could maintain the effectiveness of degrading organic pollutants for 10 days (or even longer). This study has a guiding significance for the large-scale treatment of industrial wastewater by improved Fenton technology in the future.