The successful deployment of proton-exchange membrane water electrolyzers (PEMWEs) relies on the development of an active and durable electrocatalyst for the anodic oxygen evolution reaction (OER). Although rutile IrO2 shows excellent durability due to its stable crystal structure, it suffers from unsatisfactory activity. Here, we report a partial Sn substitution strategy to trigger lattice oxygen reactivity toward boosted OER. The similar crystal structures of IrO2 and SnO2 promote uniform incorporation of Sn into the lattice of IrO2, thus retaining the durability of the pristine rutile phase. More importantly, the electron transfer from Ir to Sn through the local structure of Ir–O–Sn was found to enhance the Ir–O bond covalency, which in turn activated the lattice oxygen to participate in OER. The enhanced lattice oxygen mechanism (LOM) was further verified by in situ 18O isotope labeling in situ differential electrochemical mass spectroscopy (DEMS). Due to these attributes, the as-designed Ir0.83Sn0.17O2 catalyst showed significantly improved performance, with an overpotential of only 284 mV at a current density of 10 mA cm–2, 38 mV lower than that of the commercial IrO2. In addition, the mass activity of the Ir0.83Sn0.17O2 catalyst reaches as high as 130 A gIr–1 at 1.55 V, which is 2.58 times higher than that of commercial IrO2. Beyond that, the intrinsic stability of the rutile phase endows the Ir0.83Sn0.17O2 catalyst with excellent operational durability. This work provides a novel insight into the improvement of catalyst activity and inspires the design of highly active and stable OER catalysts.
Wang Lan-Ying,Zhuang Jun-Ping,Yu Kai-Rong,Wu Shu-Bin
Sn-Beta zeolite is a promising catalysts for isomerization of glucose to fructose, which is a key step in the conversion of biomass to various platform chemicals. Herein, Sn-Beta-H zeolite was efficiently prepared via hydrothermal synthesis by using Al-Beta. Finally, the product was
heated to 423 K for 48 h then calcined at 550 °C for 6 h to obtain Sn-Beta-H sample. The results of XRD patterns confirmed that the prepared catalyst had both microporous and mesoporous; N2 sorption isotherms showed that the main pore size centered at around 3.5 nm; TD-DTG revealed
that the Sn-Beta-H zeolite had good thermal stability with the peaks on the DTG curves was 283 °C; FTIR and UV-Vis spectra also successfully indicated that tin substitution into the zeolite framework. The effects of various reaction conditions including reaction temperature, reaction time
and the amount of catalyst on glucose conversion and fructose yield and selectivity were investigated. Under optimized operating conditions, 10% glucose solution in 40 ml water, catalyst (4 g), at 120 °C for 2 h, resulting in fructose yield of 30.8% and selectivity of 61.3%. Moreover,
Sn-Beta-H zeolite could be easily recovered and efficiently reused without significant loss in its catalytic activity.
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