According to the New York Times, Trump sought some dirt on Comey before firing him, leading some to conclude that he knew what he was doing was inappropriate:
The New York Times has also learned that four days before Mr. Comey was fired, one of Mr. Sessions’s aides asked a congressional staff member whether he had damaging information about Mr. Comey, part of an apparent effort to undermine the F.B.I. director. It was not clear whether Mr. Mueller’s investigators knew about this incident.
The NYT also reports that Trump was furious with Sessions when he recused himself because he wanted him to “protect” him:
President Trump gave firm instructions in March to the White House’s top lawyer: stop the attorney general, Jeff Sessions, from recusing himself in the Justice Department’s investigation into whether Mr. Trump’s associates had helped a Russian campaign to disrupt the 2016 election.
…
Mr. McGahn was unsuccessful, and the president erupted in anger in front of numerous White House officials, saying he needed his attorney general to protect him. Mr. Trump said he had expected his top law enforcement official to safeguard him the way he believed Robert F. Kennedy, as attorney general, had done for his brother John F. Kennedy and Eric H. Holder Jr. had for Barack Obama.
While this is all very entertaining and liberals are very excited about this new report, I’m not sure any of this stuff shows any illegal conduct.