Geopolymer‐based ceramics as catalysts or catalyst supports have attracted tremendous interests in recent years owing to their low‐cost and zeolite‐like structure characteristics. However, most of the reported works focus on alkaline‐based geopolymers, whereas the catalytic performance of acid based geopolymer has not yet been evaluated. This study aims to investigate the application potential of phosphoric acid–based geopolymer (PAG) for selective catalytic reduction (SCR) of NOx with NH3. To this end, the SCR reactivity of PAG and metal oxide (MnOx)‐loaded PAG were evaluated. Moreover, an activated carbon‐based hard template route was proposed for further enhancing the SCR reactivity of the PAG‐based catalyst. The as‐prepared catalyst under the optimal condition exhibited a high NO conversion greater than 85% in a wide temperature range of 250–350°C, which is among the top literature‐reported values, demonstrating its promising application prospect. A systematical X‐ray diffraction, X‐ray photoelectron spectroscopy, field emission scanning electron microscopy, Brunauer–Emmet–Teller, NH3‐temperature‐programed desorption, and H2‐temperature‐programed reduction spectroscopic analyses were also conducted to better understand the structure evolution of PAG under elevated temperature and the SCR catalytic mechanism of the acid‐based geopolymer catalysts. This study would provide valuable information on the potential application prospect of PAG and its modified form for efficient NOx removal.
The photoelectrocatalysis is an efficient and sustainable degradation method for organic contaminant, where the photoanode material plays a critical role. Development of novel, inexpensive, and high‐performance photoanode materials is significant to enhance the degradation performance of anodes catalysis. Herein, a novel carbon‐fiber geopolymer composite‐coated electrode with low cost and facile production was prepared by incorporating carbon fibers in a geopolymer matrix. The as‐developed photoelectrocatalyst coupled with persulfate could effectively degrade more than 98 % of rhodamine B within 6 min, which demonstrated superior catalytic activity compared with various catalysts reported in the literature. Moreover, the composite electrodes exhibited excellent reusability. The endogenous Fe2O3 and TiO2 in the geopolymer matrix were the main active materials, providing photoelectron‐hole pairs for dye molecule degradation. Significantly, the carbon fibers in the matrix effectively connected the scattered oxide species and prompted the separation and migration of photoinduced carriers while enhancing the stability of the catalysts and improving the conductivity of the matrix. When the carbon content was increased from 0 to 6 wt%, the conductivity of the composite increased by 17.75 times. This study offers a cost‐effective and eco‐friendly photoelectrocatalyst, which shows significant potential for further development.
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