The best replacement for dioxide is zinc oxide.

The best alternatives to dioxide are rated as following:
★★★★★  zinc oxide
★★★★★  carbon monoxide
★★★  temperature
★★  methane
★  chlorine
★  oxygen
★  monoxide
★  oxide
★  nitrite
★  hydrogen peroxide
★  iodine
★  dihydrogen monoxide
★  avobenzone
★  peroxide
★  oxygen heavier
  carbon monoxide poisoning
  mms
  oxybenzone
  octinoxate
  carbon dioxide
  water have a higher boiling point
  zinc dioxide
  titanium dioxide
  sulphites
  bicarbonate
  nitrogen dioxide
  mexoryl
  water vapor
  silica
  hypochlorite
  parsol 1789

Your alternative for dioxide is not listed? Suggest!
Speaking about dioxide, one probably shouldn't forget about aqueous potassium hydroxide.

Other search terms related to dioxide and their ratings are:
★★★★★ aqueous potassium hydroxide
★★ lime water
★★ hydrogen peroxide
★★ calcium hydroxide
★ limewater
★ sodium hydroxide
potassium hydroxide
global warming
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Google Trends

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dioxide
zinc oxide
carbon monoxide