Which books do you have? The original 3.5e Eberron Campaign Setting doesn't use the word "noir" much, preferring "dark" instead. There's a sidebar with a list of inspirational movies, including The Maltese Falcon, The Mummy, Raiders of the Lost Ark, etc.
The 5e book has a section in the first chapter labeled "Noir Intrigue": "Eberron draws inspiration from noir and hard-boiled fiction. It’s a world where stories don’t always end well, and where there isn’t a perfect solution for every problem. In developing characters or stories in Eberron, consider the following concepts."
Its sub-sections include "Everyone Has Regrets", "Personal Motives", "Shades of Gray", and "Something to Lose".