Black & White Web Design (UI/UX Wise)

One of my client(He has a SEO agency)need to design a website with blog. He want 100% black and white design. That means text, images everything are 100% black and white.

Is there any UI/UX research about black and white web design? Is it a good concept UI/UX point?

Note : Back and White doesn't mean that his primary color is black. Primary color is very dark grey and text color will be dark grey with pure white background in almost all places.