[Tex/LaTex] Making bold subsection-headings in math, but not bold in ToC

Question

I am writing in the document type article, and I wish to have my subsection appear in bold itself, but appear normal in the ToC. I am trying to write a chemical formula, which automatically converts the text to non-bold, when using \ce. I chose to do it like this:

\subsection{formation of $\mathbf{N_2O}$ during $\mathbf{NH_3 - SCR}$}

This will make the subsection appear bold, but also it will make the text in \mathbf appear bold in the ToC. I would like to just have the sections appear bold, and the subsections to appear normal in the ToC

Answer 1

If \ce is used, there's no need to use either \mathbf nor the optional argument of the \subsection command at all.

\documentclass{article}


\usepackage[version=4]{mhchem}
\begin{document}
\tableofcontents
\section{Foo}
\subsection{Foobar}
\subsection{formation of \ce{N2O} during \ce{NH3}-SCR}

\end{document}