The phrase 'more certainly than' is correct and usable in written English.
You can use it to emphasize how much more certain something is than all other options. For example, "He loves her more certainly than he ever has before."
Lightman solves cases more quickly and more certainly than in the real world".
More daunting, perhaps, Americans seem to have great trust in their doctors — more, certainly, than they trust the government on medical matters.
Tall and thin, with big hands and a long neck, Mr. Day-Lewis physically resembles Lincoln more nearly than many of his predecessors — more, certainly, than Kris Kristofferson, who in the 1995 television movie "Tad" had to wear platform shoes to boost him to Lincolnesque stature.
Most people would pay a substantial share of their wealth — much more, certainly, than the modest cost of a carbon tax — to avoid having someone pull the trigger on a gun pointed at their head with one bullet and nine empty chambers.
He told his party: "We know more certainly than ever before that there is a strong progressive majority in Britain, I wish more than I can possibly say that I could mobilise that majority, but I could not – I have to accept and to assert personal responsibility the fault is mine, and I will carry that alone.
The amount of suffering is immense — far more, certainly, than it would be if God's aim were to maximize worldly joy.
More together, certainly, than would have been possible apart.
More typical, certainly, than it is for us today.
Far more ambitious, certainly, than the N.R.A.'s kindergarten cop concept.
And that often requires more money, certainly, than a $500,000 license fee".
More so, certainly, than a mere two tries to one does.
