pre-noun adjectival
further; even more; additional
Pre-noun adjectival (rentaishi) used to emphasize a greater degree or additional step. Often found in formal or written contexts.
I look forward to the company's further development.
Further effort is needed.
Please wait for further information.
Further effort is needed to achieve the goal.
We wish your company continued and greater success.
We are aiming for further improvement in quality.
一層 is an adverb meaning 'all the more/still more' that intensifies a change, while 更なる is a pre-noun adjectival that directly modifies a noun like 更なる努力.
Kanji form is standard in formal writing, but the word is often written in kana.
Kana spelling is very common and recommended for learners.
Derived from the adverb さらに (furthermore) with the addition of the archaic attributive form なる of the copula なり, creating a pre-noun adjectival.