Synthesisand CH₂O-Detection Behavior of Nanoporous Ag-Coatings: An Experimental Study

The nanoporous Ag-coatings were synthesized by induction melting and via electrochemical reactions(in constant voltage/current modes) with Ag-powder and AE44 alloy as raw materials.The influence of the voltage and current on the;porosity and CH₂O-detection sensitivity was investigated.The results show that the voltage and current had a major impact.To be specific,the dielectric and Ag phases co-existed in Ag-coating.In constant-V mode,as V increased,agglomeration of Ag-cluster increased and the dissolution-rate decreased because the current density J,though changing in an increase-decrease manner,approached to an increased value.In constant-I mode,as J increased from 1.5 to 4.5 mA/cm²,the average pore-size increased from 80 to 100 nm.As expected,the nanoporous Ag-coatings exhibited excellent CH₂O-detection sensitivity.For instance,at a CH₂O-concentration in 10~50 mmol/L range,the oxidation peak was about-0.70 V,and a concentration above 75 mmol/L generated large CH₂O-oxidation current.