The short answer is no. Sennheiser e835 does not need any external power supply for operation and does not require phantom power to operate.
Does Sennheiser E835 Need Phantom Power?
The microphone does have an integrated pre-amp circuit, so it does provide some amplification of the signal. However, if you are looking for more gain or different sound quality, then an external preamp may be necessary.
Additionally, if you are using this mic in a live environment, you may find that additional gain provided by phantom power can help improve the overall sound quality and clarity of the vocals. Ultimately it comes down to personal preference and what works best for your application.
Note: Some condenser mics do require phantom power so always make sure to double-check the specs