Produce air at depth

[Fish_Whisperer]

I had a McDonald's "McGriddle," on my way to the dive site, one morning. Indeed, I most certainly DID produce air at depth!! (However, it probably wasn't anything you'd want to breathe...)

 

[Thalassamania]

My understanding is that the Russian military re-breathers do use a catalyst that breaks CO2 into O2 and C. What I recall reading is that the chemical reaction can cause a huge amount of heat and can become very unstable very easily. It is the same scrubber chemical that caused the (or at least one) fire in the MIR space station.

No. It was not a scrubber chemical but an “oxygen candle, known as the TGK generator. It contains a replaceable cartridge, a thin walled steel tube with a three-part block of oxygen-releasing mixture based on lithium perchlorate. Two parts are tablets of the chemical mixture and the third one is the igniter tablet with a flash igniter. The igniter is struck by a firing pin when the device is activated. One cartridge releases 600 liters of oxygen and burns for 5-20 minutes at 450-500 °C. The oxygen is cooled and filtered from dust and odors, and released into the space station atmosphere.

On 23 February 1997, during the exchange of an air filter, a failed chemical oxygen generator spewed a torch-like jet of a molten metal and sparks across one of the Mir space station modules, burning for 14 minutes and blocking the escape route to one of the Soyuz spacecraft. The accident was caused by a leak of the lithium perchlorate from one of the canisters.

I have seen an outfit trying to sell Russian re-breathers to the west and it always mentioned that the scrubber can be adapted and (I think) an O2 cylinder also neede to be added.

Again no. To the best of my knowledge no diving device uses oxygen candle technology, it is far to dangerous to use when there is any chance of it getting wet. What you may have been looking at is a device for emergencies in underground mines which do something use oxygen candle technology.