The fabrication of graphitic carbon nitride (g-C 3 N 4 ) has received much attention for its superior photoelectronic properties, it remains a remarkable challenge with a feasible methodology. Herein, inspired by carburization , a novel method with carbon diffusion was proposed to prepare g-C 3 N 4 nanosheets (CNNS). The carbon diffusion was caused by the gradient difference in carbon concentration between the gaseous environment and the C15 (mild steel with low carbon content) during thermal polymerization . Eventually, the CNNS with approximately 1.5 nm thickness was successfully fabricated and exhibited larger surface area (98.08 m 2 g −1 ), which was 15.42 times higher than that of bulk g-C 3 N 4 (BCN). In the evaluation of photocatalytic CO 2 reduction activity, the CH 3 OH formation rate over CNNS (2.10 μmol g −1 h −1 ) was 3.28 times greater than BCN. Meanwhile, the designed CNNS exhibited dramatic improvement on H 2 evolved rate (HER) of 2507.02 μmol g −1 h −1 , which was 6.99 times higher than BCN. More importantly, the C15 possessed the advantage of 10 times recycled to use for the fabrication of CNNS accompanied by a moderate decrease of HER. Moreover, the density functional theory (DFT) calculations were carried out based on the results. This work highlights an ingenious tactic with carbon diffusion for preparing CNNS towards renewable solar energy conversion .
Pan Zhang,Yanxi Ji,Wenya Li,Lihua Xu,Lemeng Wang,Dong Fu
The viscosities of N -(2-aminoethyl)ethanolamine (AEEA), 1,4-butanediamine (BDA) and N-methyl- 1,3-propane- diamine (MAPA) activated 2- diethylaminoethanol (DEAE) aqueous solutions were measured at temperatures ( T ) from 303.2 K to 323.2 K, respectively. The DEAE mass fractions ( w DEAE ) and the other three amines ( w AEEA / w BDA / w MAPA ) are 0.300 to 0.500 and 0.050 to 0.150 respectively. The Weiland equation was used to calculate the viscosity of these three solutions, and the calculation results were satisfied with data of the experimental results. With the aid of experimentally determined viscosity data, the activation energy ( E a) of these three solutions was predicted through the Arrhenius formula. With the help of the viscosity data and the diffusion coefficient model of CO 2 in water, the CO 2 diffusion coefficient ( D CO2 ) in these three solutions was calculated. The quantitative relationship between the calculated values (viscosity, activation energy and diffusion coefficient) and the operation conditions (solution mass fraction and temperature) was analyzed. Our results show that the DEAE-BDA absorbent has better application potential due to its lower viscosity, higher CO 2 diffusion coefficient and lower activation energy.
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