High temperature CO₂sensing properties and mechanism of nanocrystalline LaCrO₃with rhombohedral structure: experiments and ab initio calculations

Abstract

LaCrO 3 nanocrystalline powders with perovskite structure were prepared by sol-gel method with annealing at 700 C, 900 C for 4 h, respectively. At room temperature, LaCrO 3 nanocrystalline powders crystallizes as the orthorhombic structure. At high temperatures above the transition temperature from orthorhombic to rhombohedral, when exposed to CO 2 the optimum operating temperature for sensing is 360 C and the resistance of the rhombohedral LaCrO 3 sensor decreases, which is different from other p-type semiconductors. First principles calculations (GGA + U) were performed to investigate the possible CO 2 sensing mechanism for rhombohedral LaCrO 3 sensor. The calculation results show that when exposed to CO 2 , the C atom of CO 2 molecule chemically binds with the surface O atom of rhombohedral LaCrO 3 (012) surface, meanwhile the two O atoms of CO 2 molecule chemically bind with the adjacent surface Cr atoms on LaCrO 3 (012) surface. For this case, the CO 2 molecule captures electrons from the LaCrO 3 (012) surface, which is consistent with the experimental observation.

The electrical modulus and other dielectric properties by the impedance spectroscopy of LaCrO3and LaCr0.90Ir0.10O3perovskites

“…The perovskite oxide materials have grabbed considerable attention among scientists due to their electrical, dielectric, magnetic, thermal, mechanical, sensing and optical properties. [1][2][3][4][5][6][7] Additionally, the exibility in the chemical composition of these materials offers excellent possibilities in terms of control of their structures via substitution of a number of transition metals into the A or B cation sites. [8][9][10][11][12] Such properties make perovskite oxides very promising for several applications.…”

Suppression of surfaces states at cubic perovskite (001) surfaces by CO2 adsorption

“…3,4,6 In an attempt to overcome this obstacle, research focus has gradually shifted to alternative sensing materials, including various inorganic perovskites possessing prospective CO2 sensing characteristics. [7][8][9][10][11][12][13][14][15][16][17] The first efficient perovskite-based CO2 sensor was developed by Meyer et al, who discovered profound chemiresistive features of BaTiO3-containing composites. 7,8 Since then, the optimized composition consisting of BaTiO3, CuO, and La2O3 has long been the best-performing CO2 sensing material reported in the literature 4,8 until the recent development of BaSnO3-based chemiresistor.…”

Band gap modulation of SrTiO3 upon CO2 adsorption

“…Although a few traditional sensing materials (such as ZnO, 8 SnO 2 , 9 WO 3 , 10 La 2 O 3 11 ) have been utilized for CO 2 detection, reported sensitivity is too low for practical usage. 7 At the same time, various perovskites [12][13][14][15][16][17] and perovskite-based composites 18 demonstrate a profound CO 2 chemiresistive effect. Owing to their stability, electronic properties, and low production cost, this class of materials has received significant attention in sensing technologies.…”