Selective gas detection using Mn₃O₄/WO₃ composites as a sensing layer

Pure WO₃ sensors and Mn₃O₄/WO₃ composite sensors with different Mn concentrations (1 atom %, 3 atom % and 5 atom %) were successfully prepared through a facile hydrothermal method. As gas sensing materials, their sensing performance at different temperatures was systematically investigated for gas detection. The devices displayed different sensing responses toward different gases at specific temperatures. The gas sensing performance of Mn₃O₄/WO₃ composites (especially at 3 atom % Mn) were far improved compared to sensors based on pure WO₃, where the improvement is related to the heterojunction formed between the two metal oxides. The sensor based on the Mn₃O₄/WO₃ composite with 3 atom % Mn showed a high selective response to hydrogen sulfide (H₂S), ammonia (NH₃) and carbon monoxide (CO) at working temperatures of 90 °C, 150 °C and 210 °C, respectively. The demonstrated superior selectivity opens the door for potential applications in gas recognition and detection.