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Abstract MXenes are a new family of two-dimensional carbides and/or nitrides. Their 2D surfaces are typically terminated by O, OH and/or F atoms. Here we show that Ti₃C₂T_x—the most studied compound of the MXene family—is a good acid catalyst, thanks to the surface acid functionalities. We demonstrate this by applying Ti₃C₂T_xin the epoxide ring-opening reaction of styrene oxide (SO) and its isomerization in the liquid phase. Modifying the MXene surface changes the catalytic activity and selectivity. By oxidizing the surface, we succeeded in controlling the type and number of acid sites and thereby improving the yield of the mono-alkylated product to >80%. Characterisation studies show that a thin oxide layer, which forms directly on the Ti₃C₂T_xsurface, is essential for catalysing the SO ring-opening. We hypothesize that two kinds of acid sites are responsible for this catalysis: In the MXene, strong acid sites (both Lewis and Brønsted) catalyse both the ring-opening and the isomerization reactions, while in the Mxene–TiO₂composite weaker acid sites catalyse only the ring-opening reaction, increasing the selectivity to the mono-alkylated product. 

ABSTRACT In this work, we explore the application of intensity mapping to detect extended Ly α emission from the IGM via cross-correlation of PAUS images with Ly α forest data from eBOSS and DESI. Seven narrow-band (FWHM = 13 nm) PAUS filters have been considered, ranging from 455 to 515 nm in steps of 10 nm, which allows the observation of Ly α emission in a range 2.7 < z < 3.3. The cross-correlation is simulated first in an area of 100 deg2 (PAUS projected coverage), and second in two hypothetical scenarios: a deeper PAUS (complete up to iAB < 24 instead of iAB < 23, observation time ×6), and an extended PAUS coverage of 225 deg2 (observation time ×2.25). A hydrodynamic simulation of size 400 Mpc h−1 is used to simulate both extended Ly α emission and absorption, while the foregrounds in PAUS images have been simulated using a lightcone mock catalogue. Using an optimistic estimation of uncorrelated PAUS noise, the total probability of a non-spurious detection is estimated to be 1.8 per cent and 4.5 per cent for PAUS-eBOSS and PAUS-DESI, from a run of 1000 simulated cross-correlations with different realisations of instrumental noise and quasar positions. The hypothetical PAUS scenarios increase this probability to 15.3 per cent (deeper PAUS) and 9.0 per cent (extended PAUS). With realistic correlated noise directly measured from PAUS images, these probabilities become negligible. Despite these negative results, some evidences suggest that this methodology may be more suitable to broad-band surveys.