I'm not sure if people on here are from different places so I'll give some background. I'm a chemistry student on an integrated masters scheme in the uk, and I'm in my final year. Before I started my final year I could never see myself doing a phd, mainly because I thought I was not smart enough or had the grades however now I've started my final year and have begun my research project, I am enjoying the whole research side (despite loads of my reactions failing) and would love to be doing research rather than working in an office all day. I've been really hesitant to apply to any phd positions for many reasons.

Im on a 2.1 right now and will most likely being graduating with a 2.1, I am definitely gonna try my hardest to get a 1st but my low 2.1 in third year has pulled my average down. I did have some mitigating circumstances but I didn't end up applying for it as for some reason I felt it would be wrong to do so, do you guys think maybe I could still explain these if the topic came up?

I feel like I still don't know a lot to be doing a phd, the post doc I work with is insanely genius, I know he's been doing this research stuff for a while so thats probably why he knows so much but I feel like even if I reached his stage I won't know as much as he does.

And finally I'm kind of hesitant to ask my academic advisor and supervisor for references, they're both incredibly nice but do you think they'll give me one for a phd application given what my current grades are right now?

I personally got a 2:1 and many many other PhD students also achieved 2:1s at undergraduate level. So a 2:1 does not rule you out.

I got a 2:1 as well and don't have a masters. I got on to my PhD due to relevant experience.

I also went into a PhD with a 2:1 (Engineering) but wouldn't recommend it. Try to do a Masters by Research (or a taught Masters with a significant research element) in between if you can. Bit of a long shot you might be thinking but it will better prepare you for the jump from the undergrad to PhD level. Ideally you need a solid (theoretical) foundation as well as some exposure to research before tackling a PhD and in my experience a good (2:1) undergraduate degree alone just doesn’t provide that.

You might find that you struggle to get the PhD position you want with a 2:1 if you are in competition with those with a 1st but you will probably find something. If your 2:1 is very low I would seriously recommend you take a step back and consider whether your academic background is strong enough to make the journey without you fixing whatever needs fixing. It's hard enough without having the undergraduate principles secured.

By the way, if I can provide one piece of advice it would be to drop the "genius postdoc" thing. It's absolutely not true (there is no such thing as a genius) and it's potentially highly damaging to your confidence to be thinking that way. A PhD is no longer just about being academically brilliant. Yes you need to be smart but it's about hard work and an independent attitude more than anything else. It might be worth considering that this "genius" has not even secured their first permanent job yet and may yet find it hard to do so. Leave them to their own difficult life journey and just focus on yours.

I certainly wouldn't advise you saying anything about losing motivation as a reason for poorer grades in 3rd year. I also wouldn't go with a defence of "if I had studied harder I would have got a 1st" because anyone can say it. If asked, you may need to satisfy the supervisor that your lack of motivation was a one-off due to exceptional circumstances which won't happen again. This is your biggest problem I think because during the middle years of your PhD you will have no shortage of things to feel demotivated about. How can you guarantee you won't suffer a similar fate? You need to be able to answer that question.