Can silver be substituted with another chemical in photography?

Firstly, silver is not a chemical, it is an elemental metal.

If I am to presume your question relates to film (not paper) and how the latent image is laid down, then my answer is no. I must confess I'm not an expert on the history of photographic processes, but I do believe they all involved silver or silver salts where the creation of permanent images was concerned. The silver halide of today is typically silver chloride, silver bromide or silver iodide based, or a combination of those. I don't believe silver iron is used anymore. There are non-silver based printing processes, but as I mentioned, my assumption precludes these.

I also presume you are not referring to the coupling of dyes with developed silver halides in color film processing. In this case, silver is "substituted" during the color film development process.