"put serious effort" is correct and usable in written English.
You can use it to describe an attempt to do something difficult in order to achieve a desired result. For example, "I put serious effort into my job search and eventually found a great new position."
But Mandy put serious effort into her lies.
"Yes, it's a joke and, yes, we put serious effort into it but we've no idea which one takes priority".
Although Paul put serious effort into writing letters and compiling tests, he also did things that detracted from the professional-medical-board image he was trying to project.
Fairbairn said: "With interest rates at rock bottom, now is the time for the UK to put serious effort into improving our creaking infrastructure.
Somebody put serious effort into the way they were presented, complete with a preface from an unnamed "editor" who used the salesman's trick of seeming to side with a doubtful audience.
Not only does it offer a chance of substantial action despite Republican obstruction, there was a tone to the speech suggesting that Obama may put serious effort into this thing, that he may see climate policy as the big legacy of his second term.
Companies today should put serious efforts into making strong visuals to grab the attention of our audiences.
While seeking intellectual property rights (IPR) is entirely appropriate for your well-structured knowledge, putting serious effort into mapping the deep, implicit knowledge within your organization can prove equally valuable.
The company also puts serious effort into maintaining its R&D talent.
But caught off-guard by the election of Donald Trump, Google has been putting serious effort into wooing Republicans.
The outside money may be a sign Republicans are putting serious effort into keeping the seat in party hands.
