The article describes the motion of a Janus particle adsorbed at a water-oil interface due to temperature and surfactant gradient driven Marangoni stresses. Light from a laser source is absorbed by the gold plated side of the Janus colloid which generates heat and drives thermal Marangoni propulsion. On the other hand, depletion of adsorbed surfactants at the water-oil interface in the wake of the particle drive solutal Marangoni stresses that oppose the particle's motion. The research is very topical and provides new results in the growing field of active matter. The title is appropriate and catchy, although it could be more descriptive to make the article appeal to a broader audience. The abstract is concise and covers the key findings as well as the basic principle used to drive the particle motion. However, the aim of the research is not clearly stated in the abstract and the additional benefits offered by this new strategy do not stand out conspicuously.

The authors clearly state the various mechanisms that drive self-propulsion. The research objective is clearly posed, giving the readers a good idea about how the current work will lead to orders of magnitude increase in the propulsion velocity of active colloids. This is a significant advancement in the field.

The data presented in this article is convincing and the agreement with the simple theory is remarkable. Moreover, the data collapse in Fig. 4 is truly impressive and leaves no doubt in my mind that the authors have adequately captured the relevant physics in their system. Clearly, the scaling works and the relative contribution of the two opposing forces, namely thermal and solutal Marangoni stresses (captured by the dimensionless number $\mathrm{\Pi }$) is nicely represented in the experiments.

The supporting text makes it very easy for the reader to understand what the data represents and how to interpret the results. Overall, I think the results are crisp and concise. With just two figures, the authors convey a lot of meaningful information.

I agree with the authors' claim that this technique has the potential to create "unprecedented opportunities for the spatial and temporal modulation of self-propulsion". I must, however, point out that the technique is only valid for propelling particles pinned at an interface and the authors should mention that somewhere in the discussion to prevent readers from making generalized conclusions. Moreover, the final claim that the current procedure may be used as a "sensitive characterization tool for the presence of surface-active species" seems a little far-fetched. I don't believe the setup is straightforward enough (at least at this stage) to make such turnkey measurements yet. I feel that the main message is loud and clear and the importance of this research will not be diminished without that sentence.

Some additional areas where the article could use some revision:

The introduction to the field of active matter and its impact on the development of "disruptive technologies" seems rather rushed in the opening statement. Perhaps more clarity on what specific technologies the authors are referring to might help clarify the ambiguity of the statement.

The experimental methods section (on page 2) and the numerical simulation method discussed in the supplementary information describe quite nicely how the data for Figs. 2 and 3 was collected. Although I did have a hard time understanding how the authors varied the surface concentration to verify the effect of $\mathrm{\nabla }\mathrm{\Gamma }$ on Marangoni stresses. It was not until later in the article (on page 4) where the authors discuss how they add the surfactant SDS to vary $\mathrm{\Gamma }$. I believe in discussing Figs. 2 and 3, the authors rely heavily on the effect of $\mathrm{\nabla }\mathrm{\Gamma }$ to describe their results. Since there isn't a separate methods section to refer to, it appears as if this change in the concentration of surface active species just appears out of nowhere. It would be helpful for the reader to understand how the authors tune that property in the experiments beforehand so that it is easier to rationalize some of the observations later. I suggest rearranging the order of the manuscript a little to clarify how the surface excess concentration was varied in the experiments, before describing the effects in the results.

Although experimental error bars are visible in Figs. 3 and 4, I could not find anywhere how the error was calculated. Were the experiments repeated at those conditions several times or do the errors represent some kind of ensemble averaging?

A minor suggestion for the sake of clarity -- equations for $V$, $P{e}_T$, $P{e}_S$, and $\mathrm{\Pi }$ if displayed as line equations would make it easier for the reader to quickly go back and refer to them when interpreting Figs. 2, 3, and 4.