Query to List Encryption Certificate for Databases
You can join on the certificate thumbprint:

use master;
go

select
    database_name = d.name,
    dek.encryptor_type,
    cert_name = c.name
from sys.dm_database_encryption_keys dek
left join sys.certificates c
on dek.encryptor_thumbprint = c.thumbprint
inner join sys.databases d
on dek.database_id = d.database_id;


My sample output:

database_name           encryptor_type    cert_name
=============           ==============    =========
tempdb                  ASYMMETRIC KEY    NULL
AdventureWorks2012TDE   CERTIFICATE       TdeCert