Ultrasensitive and selective CuAlO2 sensor toward H2S based on surface sulfuration-desulfuration reaction

Abstract

Exploring novel sensing materials with extraordinary specificity/selectivity is essential to construct artificial gas molecules recognition chips (sensor arrays) for future environment and health monitoring. Herein, we reported the excellent H2S sensing properties of a p-type delafossite CuAlO2 sensor. Without complex size, morphology or defect control procedures, irregularly shaped CuAlO2 particles (size ranging from tens of nm to several μm) synthesized by a simple sol-gel route, exhibit an ultrahigh response (4600) toward (10 ppm) H2S molecules at 160 °C. Tiny responses (< 2) toward (100 ppm) NH3, NO2 and diverse volatile organic compounds (VOCs) molecules indicate an excellent selectivity. In addition to well-known surface oxygen involved gas/oxide charge interaction, quasi-operando spectroscopy (combing XPS, Raman, GC-MS, UPS etc.) analyzing suggests the surface sulfuration of CuAlO2 (S:CuAlO2 possessing a higher EV position than CuAlO2), which would act as a chemically switched ‘gate’ and effectively modulate the resistance of sensing channel, and thus contributes ultrahigh electrical response toward H2S. The reversible S doping-detaching and unique S:CuAlO2/CuAlO2 band alignment make delafossite CuAlO2 as an alternative novel H2S sensor with fantastic response and selectivity, and open up new opportunities for future applications.