Silicone oil infused slippery candle soot surface for corrosion inhibition with anti-fouling and self-healing properties

Creating superhydrophobic materials that effectively protect metal from corrosion would bring great benefits for human safety and national economy. However, most of these materials suffer from poor anti-corrosion and liquid repellence which severely restrict their actual applications. Recently, the slippery liquid-infused porous surface (SLIPS) was proposed to address the problems of metal corrosion. But the trouble is how to avoid complicated manufacturing processes as well as high production costs. Herein, a low-cost micro/nano-structured candle soot coating (CSC) was successfully fabricated via a facile spraying approach, which realized superhydrophobicity with the water contact angle larger than 150° and sliding angle smaller than 10°. Unfortunately, the superhydrophobic CSC possessed limited repellence against organic liquids and poor corrosion resistance. Through the infusion of silicone oil on the superhydrophobic surface, the SLIPS showing outstanding anti-corrosion capability can be achieved. The corrosion current density of SLIPS after immersion in 3.5 wt% NaCl solution for 2 h is 10 and 100 times smaller than that of the superhydrophobic CSC and magnesium sheet, respectively. Moreover, the long-time corrosion behavior of SLIPS was investigated by the electrochemical impedance spectroscopy, which further indicated that SLIPS presented a superior application value in anti-corrosive protection. Furthermore, the water contact angle of SLIPS changed slightly after physical cutting compared with the original contact angle, suggesting that SLIPS behaved smart self-healing property. From the comparison of the anti-corrosive and liquid-repellent properties towards the superhydrophobic CSC and SLIPS, there is no doubt that the as-prepared SLIPS would play a significant role in many fields.