Inside an OSRAM AirZing photocatalytic air purifier 

Yay :) I got quite excited about your video (since I am a fan of the channel and now you talk about the topic I'm researching for the past 15 years). TiO2 is a photocatalyst and is one of the most popular ones - it all started in 1970s with a failed experiment by two Japanese - Honda and Fujishima. The principle is that it TiO2 is a semiconductor (it is also called heterogeneous semiconductor photocatalysis) and when excited with light larger than its bandgap (3.2 eV or UV with lambda < 384 nm) it generates charge pairs (pretty much what happens in solar cells as well). If there is a molecule adsorbed on the surfaces, and these charge pairs (electrons and holes) reach it - you can oxidation and reduction reactions (and can break down organics). It works, quite well (even under modest UV illumination). There are some issues, however - in humid air you can water layers on the surface, which (in one hand help photocatalysis, because water can mediate the process forming hydroxyl or superoxide radicals and increase the efficiency since they have longer lifetimes, compared to the photogenerated charge pairs), but on the other hand it (water) can have detrimental effect on the overall process, blocking hydrophobic molecules from reaching the surface. There is also the entire issue of photocatalyst deactivation. My PhD thesis was all about photocatalytic air purification (using TiO2 coated windowpanes) and it is very effective against common contaminants in lab scale experiments (however in the real world there are other issues - but all in all it work - probably not as effectively as ozone, but with less maintenance and energy consumption). And regarding the filter mesh - not all TiO2 is photocatalytic, it needs to be in the anatase form and nanostructured (food-grade stuff is made of larger particles and usually is rutile). So - in this case they either probably coated the porous substrate with a thin layer of TiO2 sol (it is a liquid precursor of TiO2, which gets converted into the material after heat treatment - in this case it is important what the base material is, since titanates with lower activity may be formed // however the gimmick factor will be the same), alternatively - a better solution will be to start with Ti-metal foam and anodise it to form a TiO2 layer ontop (you need no more than 100 nm thickness to have photocatalytic effect).

From exploding caps, random liquid distillations and carbonizations, to informative teardowns and circuit analyses. This channel has it all. And it's still one of my favorites, even after all these years.

I remember seeing a company making windows using a titanium dioxide layer on the surface for self cleaning. Apparently the reaction from sun light helps break down the dirt on the glass then when it rains the dirt washes off with no streaks as the microcrystalline titanium dioxide is hydrophobic. The glass was supposed to work quite well.

Probably titanium dioxide on a nickel foam. Mostly because that's easy to make, has a large surface area, and lets tons of air past.

Loved the sound effects to describe how the UV light bombards the nasties entering the air purifier😁 I learned something about the use of Titanium Dioxide, I heard it was used in toothpaste and paint, but this utilisation was news to me 👍

If you’ve never used an air filter these are great. ru-vid.comUgkx_dppjvjF8BYEmPSDTcgCUdRsgWYLXNHN I ended up with three after starting out with one. The noise level depends on the 1-3 settings with how hard you want the machine to work. You can also upgrade the filters and get one better for pet hair and smells which is a must have in my home. I noticed the air seemed lighter and easier to breathe when running the machine for the first time. Works great every time. Highly recommended!

I would assume that it increases surface area for more reactivity. A small volume but large surface area due to the porous nature. This would increase the reaction rate. It is very good at reacting with organic chemicals but poor with inorganic. When UV radiation at energies larger than the band-gap energy of the TiO2 crystal (3.2 eV for anatase; 3.03 eV for rutile) is absorbed by the catalyst, an electron is promoted to the conduction band, creating a pair of a negatively-charged free electron and a positively-charged electron hole. The electron-hole pair migrating to the TiO2 surface has strong reducing and oxidizing activities. The hole in the valence band reacts with water to produce hydroxyl radicals (.OH). From "Application of ultraviolet light assisted titanium dioxide photocatalysis for food safety: A review". I imagine the filter should be removed and washed as the material from the above reaction would be somewhat attached or reacted with the mesh. By washing it you physically remove material This "recharges" the TiO2. The ROS can disrupt and damage cell functions and structures, and cause chemical modification or cleavage of the DNA and cell membrane. UV-A, UV-B, and UV-C light sources were used with TiO2 and it was shown that the combination led to structural changes in the super-coiled plasmid DNA and genomic DNA of E. coli. Photocatalysis is not limited to application of UV-C light. When combined with UV-A, and UV-B, TiO2 has proved to be less effective than UV-C for inactivation of pathogenic bacteria, E. coli. From "Application of ultraviolet light assisted titanium dioxide photocatalysis for food safety: A review".

Man I really enjoyed those sound effects of the transformation from dirty to clean air. Really helped me visualize the process happening.

It's probably just a titanium metal mesh. Titanium is one of those metals that forms a passivation layer in air, so that's where the titanium dioxide would come from.

I watched a video on the action lab channel recently where he explained that titanium dioxide is actually clear. The white colour is like the white colour of snow, from many small particles each of which is actually clear. He also explained why a layer of it produces the rainbow colours by interference between the light reflected from the metal surface and the oxide surface above it.

Titanium dioxide is actually transparent in thin films (it's commonly used for optical coatings and such), so it's perfectly plausible that the metal mesh substrate is coated in titanium dioxide, or if the mesh is actually titanium itself, has had a thin oxide layer grown on it. Supported catalysts like that are pretty common, because it results in a cheap, durable, high surface area. I do want to mention that while the claims may seem a bit like marketing wank, photocatalytic activity of TiO2 thin films has been an area of study for quite a while now. Ben over at Applied Science has a video about TiO2-coated self-cleaning glass, which has potential applications in high-rise buildings where window washing is a bit of a pain.

As others have pointed out, titanium metal forms a passivation layer of Ti02 in air and a metal mesh is much more useful from a mechanical point of view. What puzzles me is that it’s illuminatied from the wrong side, i.e. the particles and virus’s etc that you wish to destroy are more likely to collide with poorly lit bits of the mesh. Not that I suppose it makes much difference, it’s such a small device that I doubt it’d have much effect on anything larger than a sandwich box.

Clive's air was insufficiently pure About one fix, he wasn't quite sure This photocatalysis Called for more analysis To determine if it was the cure

this would be fun to test, you could always put this thing, a voc and a voc sensor in a sealed box and watch it go. would be more complicated to sample the air for other compounds but still relatively simple. weigh the filter before and after

I was researching how to make a DIY photocatalytic air purifier when I found your video. I had already discovered a source of TiO2 screen mesh available from either Europe or China, which was available in 3, 5, or 10 mm thick mesh. It had the same grey color that you questioned in this video. I thought the same thing but must assume that when it is sintered onto the mesh or somehow impregnated into it, it changes its color, but I'm not a chemist, so I may be wrong. This device is way easier to buy than to build one, so thank you!! Brilliant deconstruction of the tech too!

1:30 It's a little known fact that the laser blasts during the trench run in Star Wars were actually UV blasts to freshen up the air in the trench...

When you look at the magnified picture of the filter at 4:23 just the right way: cross-eyed and and then defocus, you can see a man dancing and singing into the microphone. Well done, Clive!

Clive, I'd say your summary of the sound is the best extent of this *science* of light purification there is.

Big Clive upping his Hollywood production game, now with added sound effects!

I think this actually.....kind of ....is... a plausible mechanism device??? There are in fact lots of papers all over on this and indeed most of them seem to be using ~370nm UV light to irradiate the TiO2 because this is in fact right around the bandgap for that material and maximum absorption should happen around there. And of course that's a reasonable wavelength for GaN LEDs to be producing a significant amount of light at (as opposed to UVB or C). I think this may actually work and not just be more quacky landfill fodder. You should test it by putting it into a totally sealed glass container with a small amount of alcohol or acetone and then run the device for a while inside. Open it and see if you still smell the VOCs. Repeat it with the LEDs shorted and see if there's a difference.

"Pho-tonic" does it do induction ? I' AIN'T HAVING IT !

Titanium oxide is actually clear it just looks white when it's in a powder form the same way that snow looks white even though water is clear

What a breath of fresh air from our friend Clive. I would have thought the mesh is a metal of some sort, but with the blow-up photo from Clive, shows it has a more complicated pattern to it. Therefore, I recon it may be made of a natural and organic sponge. Whether it is a natural sponge or not, I would say it has been dipped with a Titanium Dioxide coating. This process in turn then causes a reaction and why it looks like a spongy off gray metal. The theory of how it works looks clear, but does it do what it says on the tin. With any of these devices to clean air or give out positive ions etc to help one's environmental space in a vehicle or room needs to be proven properly.

Years ago I examined some large photocatalytic air purifiers made by a company that no longer exists. They seemed well made and well documented and included a HEPA filter. These units were designed to be installed in medical offices and hospitals. Those units used UV-C tubes that had an aluminum grid with 1/2" openings before and after the array of 2 or 4 UV bulbs. The grid was similar to those sometimes found over office fluorescent light fixtures. The grid was painted with a titanium dioxide paint that had a coarse texture. The HEPA filter was mounted downstream of the lights and grids and was made to fit the inlet of an HVAC air handler. I assumed the UV-C did all the work and the catalysis was bunk. I have used an open pore polyester filter material that would look just like the filter you have if it had been sprayed with a light coating of white paint. As you mention, white paint is usually pigmented with titanium dioxide. I very much doubt that the UV-A does anything useful, but I've been wrong before. Once. In 1981.

good to see real UV light's for a change.

I love the "EUMarket" label on the PCB. Probably put there to distinguish between non-eumarket/eBay version with fake UV LEDs. The original design :)))

The mesh would start out as just regular plastic sponge, and then it's been coated in a layer of titanium dioxide. The reason it doesn't look very white is probably just that it's a very thin layer and some of the black sponge underneath is showing through. If you squeezed and smushed it a few times all the titanium dioxide would probably start flaking off. Alternatively, a more expensive process they might have done it to bake the sponge at a high temperature, the plastic vaporises into nothing and the the titanium dioxide + some binder sinters together and leaves a hard ceramic sponge, but probably not what they've done here.

The amount of air flowing through the device is dwarfed by just opening up a window or turning on the air conditioner. Probably doesn't do much, but theoretically it should work (given a room thats 5 inch x 5 inch)

I enjoyed the sound effects

All three of my heat pump interior heads units came with two of those to install. They were labeled for deodorizing. Looked like the exact same color material.

Hi Cleave, it is very common solution: porous carrier coated with functional material. In humane words: it is titanium or titanated nickel sponge coated with tiandioxide. Metal sponge is mechanical stable and cheap, TiO2 supports the photochemical oxidation of the negative air components on its surface. Looks cool, cleverly grounded, but functionality remains questionable.

A local paint manufacturer here markets a special paint loaded with TiO2 and CaCO3 that kicks out NOx from the air by catalyzing it with water to form nitric acid, which then reacts with the CaCO3 to form CO2 and Ca(NO3)2 which gets washed away with rain or at least that's what their marketing blurb says lol

You need Anatase Titanium dioxide...Rutile form is not very photocatalytic. I work with photocatalysts as a professional. Ask any question you like.

There was some research done on using titanium dioxide paint on pools so sunlight would keep algae from growing.

I recall that in Milan they did something like this on a larger scale, they painted a couple road tunnells ceiling and a multifloor parking/bus station with a TiO2 paint and scattered UV-A lamps along the standard place illumination. I'm curios about the results of the experiment, so far in the parking the just replaced everything with LED illumination

Titanium dioxide is used in self cleaning glass surface coating, Sutch as pilkington self cleaning glass.

Titanium dioxide can also be used an additive in concrete if you want a whiter finish without bothering with paint. My guess is that's how they make the roofing tiles as well given that concrete is a pretty common material for those. Also fun fact. The most expensive color additive to concrete would be blue which is achieved by adding cobalt if I remember correctly.

I initially read your thumbnail as "postapocalyptic." I really should take a sip of my coffee before starting in on RU-vid.

Your air purification sound effect made my day🤣 Your humor never gets old!

I think your bag of titanium dioxide is 2 years past its its expiry date lol... great video as always Clive

I am sure BigClive will make a giant version of the cleaner for all of his city. He will be known as the BigBreather and introduced in the hall of Fame of the City ❤️

Interesting that you mention they're experimenting with putting titanium dioxide on roof tiles to help "clean the air". I imagine if it makes them lighter coloured then it might help reduce the absorption of heat and reduce the cost of cooling in summer. At least that's the reason why they're looking at banning dark coloured roofs on new houses in my state. Which is probably a good idea considering how hot an Australian summer gets (although surprisingly not so much for the last week).

6:18 (Someone else will point it out if I don't :)) since that diode is labelled "TVS1", I suspect it's intended to protect against voltage spikes rather than reverse polarity - though that likely doesn't invalidate what you said about it blowing the fuse if it did see reverse USB polarity! Are voltage spikes on USB supplies actually a concern in practice? Or is this just because it's for cars/etc? 🤔

With its size, and the fact that it's only going to run while the car is running AND while driving even with the cars blower turned off some air still comes from the vents and small holes and such in the car, it's not going to make any difference besides you having a little less money from buying it. Also I used to work at a car rental, if people can stink up a rental car in a few days, I hate to think what their own cars are like and that little think won't put even the tiniest dent in the stink

The "gadoow gadoow gadoow" sound really made me smile.

The titanium dioxide 'screen' looks more like titanium sponge used for pyrotechnics. The pyro sponge is granular though, not a sheet. Bed wetters and Karens. Awesome!

Love the sound effects

You generally want a solid catalyst to be very small particles which gives a tremendous surface area. I suppose you could make something like a sintered frit of pure titanium dioxide but it probably wouldn't be any better than what they have done here which I would guess is capture particles on some sort of metal foam. I'm highly sceptical of any device like this though. I'm sure the UV is causing some reactions to take place on the catalytic surface but what is being produced? Changed is not necessarily better.

Many white metal powders changes colour when they're sintered, and I'm guessing they've just mixed titanium dioxide with other metal powders of lower melting points. I do think the process of UV light on titanium dioxide as a concept works. But I don't think this product does it at a scale where it practically matters. If we were talking 10W of UV on a high quality catalyser (think several m2 of surface area) it would probably be useful for small enclosed spaces like a vehicle or small room.... that is, if you have a problem with bacteria, fungus, virus and whatnot in the first place.... But this, as a product, seems like a solution in search of a problem. Or a product which is designed to make you think you have a problem...

I have a Mosquito trap that uses fan suction and UV bulb (it says 365 nm), it claims that the surface below the bulb is coated with titanium dioxide, which creates CO2 to attract the mosquitoes and then get sucked by the fan. It works, but I don't know how accurate the claim is.

All particles smaller than 100 nanometers (millionths of a millimeter) are generally referred to as nanoparticles. Special about them is that they often have different physical properties compared to larger particles. Nano-TiO2 is not white like conventional TiO2 powder, but transparent. In sunscreen, for example, it absorbes UV light, but remains invisible on the skin.

the simple problem with these gadgets is they are ridiculously to small to do anything. considerer how much air flow goes through a car cabin when your driving. its cleaning 100,000th of that. same thing with the ones in ducts etc, airflow is way to high for the size of the units/leds.

As an auto body repair tech I am in a lot of cars and trucks. Few have the time to clean up before they drop their car off. Most vehicles are quite smelly! Smokers. Fast food eaters. Dairy farmers. Mini vans full of children. Dope smokers. Beer drinkers. Dog lovers. ( thats me) If that unit works, It isn't nearly big enough to do any good!

Seconds into "flat-earthers", I peed a little. That was the perfect sprinkling of sanity for my evening.

I was laughing at your sound effect of the UV cleaning the air.

Cool. Does that mean you can use it as a tanning booth with the filter so you can get a freckled face? I am sure that'd sell!

Chemist friend has previously told me that titanium dioxide mesh can be refreshed with a quick bath in nitric oxide, assuming it's titanium all the way through. The photocatalytic effect shreds hydrocarbons, fwiw.

Titanium Dioxide is a pain. I work at a paint factory and we had a TiO2 contamination in a tank and it ruined like 3 batches of expensive automotive paint.

I've got one, and it does light up at the top.

Please think of a way to add an ozone inside, maybe to replace the fan? I wil love to see that ! Great content great knowledge share Clive thanks!

Thanks from Texas Clive

1:19 THIS is why I am subscribed. Highly technical details explained in layman's terms.

You're obviously wrong about the diode, it isn't reverse polarity, it's even marked TVS, so it is to ground out transient voltage spikes, basically a high voltage zener across positive and negative, as you well know.

I found my new text alert! Thanks, Clive! “Ba doo, ba doo, ba doo!”

Where I work, we have Austin Air Healthmate Plus Air Purifiers though out the building Anyway I went to Osram's website and was reading about that unit.

I have noticed that there are either through holes or some form of cooling for the LEDs near the UVA Leds.

05:23 - "AAAAAGH FOCUS YOU FAKKK"!!! hahaha, good old AvE 🤣🤣 👍😎🇬🇧

3:48 Actually, titanium dioxide is on the way out as a food additive, at least in the EU: en.wikipedia.org/wiki/Titanium_dioxide#Possible_carcinogenicity_by_ingestion

That filter looks like a vacuum sintered film. Test it in a fridge, it might work better than the others you've featured for them. Thanks, good luck.

Ikea sells a range of air purifiers now, might be a bit too big and pricey for you but might be good to look at and see if they're worth the price.

Osram is a well established and reputable company, so it would be reasonable to expect that the unit will perform as advertised. How effective it is might be a matter for debate but it will work to some extent, unlike some other similar products from the Far East.

Not my area of expertise, but yes, TiO2 is indeed a photocatalyst. Any time you have any surface molecules from the air constantly bump into it, and sometimes they stick to it for a while before leaving. This happens for O2, N2, H2O, CO2, smelly molecules, really anything you have in the air. And if you illuminate the TiO2 with UV, suddenly the surface starts "zapping" whatever molecules happen to be on the surface. Some of them will just get kicked off the surface, but chemical reactions can also happen. I would imagine it would mostly result in smelly organic stuff getting oxidized.

our high end leds grow light use samsung 301b,and osram reds,so this should be interesting they use osram,only thing were finding uv b leds are killing the L90 too fast,and uva isnt in the right range for plant stressors for resin increase,so hope they get a handle and make uvb leds cooler in time

I note the PCB reads "UVLED-EUMarket V1.0" in the bottom left. I wonder if a US and AUS/NZ version differs at all, and if so, how it may differ. In AU, our USB is as universal as anywhere else I imagine.

For the photocatalytics to work the TiO2 has to be in nanoparticle form. And usually the smaller the particle size is the darker the substance looks. Platinum black is a good example.

The photocatalytic activity of TiO2 depends on the crystal structure. The powder used for paint usually has low amounts of the higher activity forms because it will break down the paint. Nano-size particles of TiO2 are clear, not white. Like the newer not-white zinc oxide and titanium oxide sun screens. Washing the mesh probably gets dust out of it. The catalyst only works on things directly in contact with it, so large particles can't effectively be broken down. The range is only as far as an OH radical can get before reacting with something, so a few nm, I think.

It's bloody expensive for what it is. $84 AUD for the updated version. I'd like to see definitive proof it actually works before purchasing it.

looks like Tio2 catalysed UV mediated Ozone generator, the low ozone production doing the work.

Titanium metal is very silver, even more than Aluminum. Both turn white when ground into a powder.

Is it really Osram, I would have at least expected a micro with PMW and led current supervision?

5:24 AvE love shout out!

High surface area mesh and maybe the method of impregnating the mesh alters the colour but this would be useful for curing UV stuff and exposing small DIY PCB's prior to etching, I dunno... a few 'Hacks' come to mind.....cheers.

I am wondering, would this "photocatalyze" the VOC's produced when 3d printing with materials that release toxic stuff (e.g. ABS, ASA)...

BDEW BDEW BDEW!!! best science explanation ever.😃

Spongy mesh is to obtain high surface. Whatever the process is it is constrained by the scrive surface. The system could be actually effective for those contaminants affected by TiO2 photo-catalisys, like NOx. I don't have infos about effectiveness on other contaminants.

I guess the mesh absorbs light like sound insulating foam absorbs sound. It looks white in the magnified image.

There you go, my phone finally has a new voice... Settings>Audio>Notifications>"Ultraviolet energy PTEW PTEW PTEW". 🤣 😂

The kicker is that it needs H2O as in water in the air to work, the dryer the air the less its going to work. For the grey color it is more efficient than white colored TiO2 as it is mentioned in wikipedia article about photocatalysis. It would be better to let sunshine in to the mesh, more efficient that way, so no need for any LEDs, any light source non-UV will do also, less potent of course.

10:05 The thickness of the coating and the very nature of being a mesh probably is responsible for looking like it does. On your zoomed pictures, it looks quite white, tho.

ive never seen anyone remove a twist tie like that - sliding if off the wire ALWAYS untwist ! always !

If it's pure titanium, it will form a thin layer of oxide on the surface, as soon as it contacts air. Maybe that is enough. It could be thin enough to not be visible. You could try heating it and see if it becomes whiter when the oxide layer gains thickness.

It's listed on Amazon Australia for $84 - doesn't look like it's worth that. I imagine it would take a long time to process all the air in your car, and then you ruin it all if you open the door or window and let the fresh air in.

Photonic reaction, a mad bloke from Kent smashes things with a hammer

Some sort of nickel foam coated with TiO2, I'd venture, similar to an auto catalytic converter, minus the $$$ platinum group metals. The stuff at magnification looks a lot like the interior of a bad weld with porosity after you start grinding on it, not that I would have ever done such a thing. 😁

The key word in the blurb is "helps" helps purify this is a get out word advertisers can use.. if you jump up and down you can say you are helping the earth to change orbit. Even if it purified two molecules they can legally say it helps purify.

5:52 You have a fan . Then you have a fan-cy circuit

Clive my friend, very interesting as usual. My questions are simple: will a single unit clean the air in a family car and should I buy one? Thanks Clive Bob England

Those LED's should be around 365nm (blue light) and do an amazing job destroying viruses, as opposed to cheap units that have the not very effective 385nm-395nm (purple) LED's. Someone said they thought the LED's were on the wrong side of the mesh. I disagree cause they will destroy anything that gets through the mesh. Those 365nm LED's are alot "hotter" than people realize. Un-diffused they can burn your skin and retinas. I have a couple of high power 365nm flashlights in the 365nm range. They are the Convoy C8 and the UVBeast V3. Both are the best out there on Amazon, but the Convoy C8 is more intense with it's single 365nm LED than the UVBeast V3 with it's three 365nm LED's. Both have patented filters built in to purify the light even more. Now i'm curious if these lights will kill the stank of the wife's WinterVag. {0.o} 😆😂🤣

Awesome big Clive

Reminds me of those low power heaters you plug directly into a socket and they claim they're better than a much more powerful heater in a more convenient location, only in this case it's a teeny tiny filter thing that is very very small fraction of an actual air filter that does the filtery thing... :P