{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,20]],"date-time":"2026-03-20T20:13:53Z","timestamp":1774037633761,"version":"3.50.1"},"reference-count":50,"publisher":"MDPI AG","issue":"14","license":[{"start":{"date-parts":[[2021,7,8]],"date-time":"2021-07-08T00:00:00Z","timestamp":1625702400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100001809","name":"National Natural Science Foundation of China","doi-asserted-by":"publisher","award":["No. 62064011"],"award-info":[{"award-number":["No. 62064011"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100001809","name":"National Natural Science Foundation of China","doi-asserted-by":"publisher","award":["No. 11964037"],"award-info":[{"award-number":["No. 11964037"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>Formaldehyde (HCHO) gas sensors with high performance based on the ZnO\/CuO heterostructure (ZC) were designed, and the sensing mechanism was explored. FTIR results show that more OH\u2212 and N\u2013H groups appeared on the surface of ZC with an increase in Cu content. XPS results show that ZC has more free oxygen radicals (O*) on its surface compared with ZnO, which will react with more absorbed HCHO molecules to form CO2, H2O and, electrons, accelerating the oxidation-reduction reaction to enhance the sensitivity of the ZC sensor. Furthermore, electrons move from ZnO to CuO in the ZC heterostructure due to the higher Fermi level of ZnO, and holes move from CuO to ZnO until the Fermi level reaches an equilibrium, which means the ZC heterostructure facilitates more free electrons existing on the surface of ZC. Sensing tests show that ZC has a low detection limit (0.079 ppm), a fast response\/recovery time (1.78\/2.90 s), and excellent selectivity and sensitivity for HCHO detection at room temperature. In addition, ambient humidity has little effect on the ZC gas sensor. All results indicate that the performance of the ZnO sensor for HCHO detection can be improved effectively by ZC heterojunction.<\/jats:p>","DOI":"10.3390\/s21144685","type":"journal-article","created":{"date-parts":[[2021,7,8]],"date-time":"2021-07-08T10:42:17Z","timestamp":1625740937000},"page":"4685","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":20,"title":["Study of Highly Sensitive Formaldehyde Sensors Based on ZnO\/CuO Heterostructure via the Sol-Gel Method"],"prefix":"10.3390","volume":"21","author":[{"given":"Jing","family":"Liu","sequence":"first","affiliation":[{"name":"Xinjiang Key Laboratory of Solid State Physics and Devices, Xinjiang University, Urumqi 830046, China"},{"name":"School of Physical Science and Technology, Xinjiang University, Urumqi 830046, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Yan","family":"Chen","sequence":"additional","affiliation":[{"name":"Xinjiang Key Laboratory of Solid State Physics and Devices, Xinjiang University, Urumqi 830046, China"},{"name":"School of Physical Science and Technology, Xinjiang University, Urumqi 830046, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Hongyan","family":"Zhang","sequence":"additional","affiliation":[{"name":"Xinjiang Key Laboratory of Solid State Physics and Devices, Xinjiang University, Urumqi 830046, China"},{"name":"School of Physical Science and Technology, Xinjiang University, Urumqi 830046, China"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2021,7,8]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"15682","DOI":"10.1021\/jp302129j","article-title":"CuO\/ZnO Heterostructured Nanorods: Photochemical Synthesis and the Mechanism of H2S Gas Sensing","volume":"116","author":"Kim","year":"2012","journal-title":"J. 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