Methane is a very stable molecule and less reactive compared to most other hydrocarbons. Non-catalytic methane decomposition (as opposed to stream reforming) requires high temperatures (1200+ °C), whereas catalysts can reduce this temperature significantly. In theory, the addition of light at or near the frequency of the C-H stretch vibration of methane (about 3000 wavenumbers) could promote conversion, requiring either lower temperatures or producing higher yields. Laser or even non-coherent light could do this. However, the cost and energy required to produce the light will probably exceed any benefit in temperature or yield. The following are some useful references for both catalytic and non-catalytic information:

Hi,

The reforming of methane is possible with or without catalysts. However, the with catalyst an alternate lower activation barrier is provided so that the same reaction can take place at a lower temperature.

Several studies have reviewed the reforming of methane without using catalyst, you may refer to the literature below:

DOI: 10.1039/c9ra09835f

Article A review of solar methane reforming systems

Article Solar thermal reforming of methane feedstocks for hydrogen a...

Thanks