Tannic acid induced surface functional strategy to synthesize Ni-doped SnO2 nanosheets for enhanced HCHO sensing

Abstract

Surface functionalization is a promising strategy to modulate the electronic and surface properties of metal oxide semiconductors. Here, we report a tannic acid (TA) induced surface functional strategy to synthesize Ni-doped SnO2 nanosheets. Benefiting from the abundant polyphenolic and catechol groups, the linkage of TA not only exhibit high affinity to various substrate, but also show powerful chelating ability to metal ions. Hence, Ni ions can be highly dispersed on the SnO2 nanosheets via TA, TA linkage also can prevent the aggregation of Ni ions during pyrolysis, and Ni substitution in SnO2 crystals can be obtained. As a proof-of-concept demonstration, the TA-Ni/SnO2 sensor is fabricated to detect HCHO, and exhibit superior sensing performance at low working temperature of 80 °C (Ra/Rg = 184.3), excellent sensing selectivity and long-term stability. Detail experimental and theoretical calculation demonstrate the highly dispersed Ni substitution active sites facilitate the generation of surface O2–(ad) species, and the electronic structure also can be modulated to exhibit high affinity to HCHO, hence, the synergistic effects contribute to the enhanced sensing performance. Our work paves the way for versatile surface functionalization to synthesize advanced materials for application in catalysis and sensing field.