You've made it to the email page... I see you are a keener.
Below is also a sample email that I sent when I began reaching out to prospective supervisors. I tried to make contact with every potential supervisor I was interested in working with for my master's. I had heard that if you reach out, they would be 'more likely to remember you during the admissions process.' This assumption might be true... but I don't know for sure lol... I am not a professor.
So, on the one hand, I did it to try to give myself the best 'chance' possible of getting accepted. Whether that meant my one simple email might make the difference between me getting accepted or not. I'm 100% sure that it's not the deciding factor, so don't worry if you haven't done this yet, and your application is already submitted.
However, and on the other hand, I was also genuinely interested in working with the professors I identified. I liked their research areas and wanted to know how they could support me and my ideas during my graduate school journey. I also read a lot of their work and honestly thought it would be cool to chat with them! So whatever your reason, sending that introductory email is worth a try.
Yes, I attached my C.V., and yes she did respond and we had a lovely phone call. Yes... I did get accepted into this program!!
NOTE: the date I emailed... this application was due in January 2018. You should reach out a minimum a month or two before. Shows you're committed and that you are thinking about it a head of time. Also, professors are really busy so you want time on your side when it comes to scheduling a phone call.