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arxiv: 1907.04773 · v1 · pith:477SX2B6new · submitted 2019-07-10 · ⚛️ physics.chem-ph

Eppur si riscalda -- and yet, it (just) heats up: Further Comments on "Quantifying hot carrier and thermal contributions in plasmonic photocatalysis"

Yonatan Sivan , Joshua Baraban , Yonatan Dubi This is my paper

Pith reviewed 2026-05-24 23:21 UTC · model grok-4.3

classification ⚛️ physics.chem-ph
keywords plasmonic photocatalysishot carriersthermal effectstemperature measurementnon-thermal contributionsexperimental flawscatalyst temperature
0
0 comments X

The pith

Inaccurate temperature measurements led to false claims of non-thermal effects in plasmonic photocatalysis.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

This paper contends that experimental flaws in measuring catalyst temperatures caused earlier reports to mistake thermal heating for non-thermal hot carrier effects in plasmon-assisted reactions. The authors point to default thermal camera settings and misplaced thermometers as sources of underestimated temperatures, which in turn produced apparent evidence for a novel mechanism. They argue that when temperatures are properly accounted for, the observed reaction rates align with conventional thermal theory, removing the need for non-thermal explanations. A sympathetic reader would care because correctly identifying the dominant mechanism determines how to design more efficient plasmonic catalysts for chemical processes.

Core claim

The central claim is that the additional data in the Response further validates the criticism that inaccurately measured temperatures, lower than the actual temperature of the catalyst, led to incorrect claims of non-thermal effects. Flaws such as the use of default settings for the thermal camera and incorrect positioning of the thermometer are identified as likely causes. Additional faults in power determination, normalization of the rate to the catalyst volume, and misconceptions regarding the thermo-optic response are noted. The burden of proof for a novel physical mechanism has not been met since the data can be modeled by conventional theory.

What carries the argument

The central mechanism is the underestimation of catalyst temperature due to improper use of thermal imaging and thermometer placement, which masks the true thermal contribution to the reaction rate.

If this is right

  • Correcting the temperature measurements eliminates the apparent evidence for non-thermal effects.
  • Reaction rates are consistent with thermal activation alone.
  • Proposals of novel mechanisms like hot carrier contributions require more rigorous temperature control and validation.
  • Normalization issues and power determination errors further undermine the original claims.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

  • Similar experiments in the field may have suffered from the same measurement inaccuracies, suggesting a need for standardized thermometry protocols.
  • This could shift focus in plasmonic photocatalysis research toward optimizing thermal management rather than pursuing non-thermal pathways.
  • If thermal effects dominate, catalyst designs should prioritize heat dissipation or absorption properties.

Load-bearing premise

The assumption that the flaws in the thermal camera default settings and thermometer positioning in the original experiments directly resulted in the reported lower temperatures that created the appearance of non-thermal effects.

What would settle it

An experiment repeating the original setup but with corrected thermal camera settings and accurate thermometer placement, showing reaction rates that exceed what thermal models predict at the true temperature.

Figures

Figures reproduced from arXiv: 1907.04773 by Joshua Baraban, Yonatan Dubi, Yonatan Sivan.

Figure 1
Figure 1. Figure 1: ), an effect that is undesirable due to the resulting lack of selectivity and high practical costs, was not fully elucidated. E Electron distribution probability EF ¯hω ¯hω 0 0.2 0.4 0.6 0.8 1 non−thermal electrons non−thermal holes thermal electrons FIG. 1: Schematic illustration of the electron distribution in a metal illuminated by continuous wave (CW) radiation. The blue solid line represents the equil… view at source ↗
Figure 2
Figure 2. Figure 2: FIG. 2: ( [PITH_FULL_IMAGE:figures/full_fig_p006_2.png] view at source ↗
Figure 3
Figure 3. Figure 3: FIG. 3: (Color online) Fig. 1 of [6]. The distance between the thermocouple and the sample is [PITH_FULL_IMAGE:figures/full_fig_p008_3.png] view at source ↗
Figure 4
Figure 4. Figure 4: FIG. 4: (Color online) A schematic illustration of the temperature profile in the photocataltysis [PITH_FULL_IMAGE:figures/full_fig_p010_4.png] view at source ↗
Figure 5
Figure 5. Figure 5: FIG. 5: (Color online) Left panel: reaction rate as a function (inverse) temperature, points are [PITH_FULL_IMAGE:figures/full_fig_p015_5.png] view at source ↗
read the original abstract

Our Comment [Sivan et al., Science 2019] (as well as its longer version [Dubi, Un, & Sivan, ArXiv 2019], and the supporting theoretical studies [Dubi and Sivan, ArXiv 2018]) on recent attempts to distinguish thermal and non-thermal ("hot carrier") contributions to plasmon-assisted photocatalysis [Zhou et al., Science 2018] initiated a re-evaluation process of previous literature on the topic within the nano-plasmonics and chemistry communities. The Response of Zhou et al. attempts to defend the claims of the original paper. In this manuscript, we show that the Response presents additional data that further validates our central criticism: inaccurately measured temperatures (that are lower than the actual temperature of the catalyst) led Zhou et al. to incorrectly claim conclusive evidence of non-thermal effects. We identify flaws in the experimental setup (e.g. the use of the default settings for the thermal camera and incorrect positioning of the thermometer) that may have led Zhou et al. to make such claims. We further show that the Response contains several factual errors and does not address the technical problems we identified with the data acquisition in [Zhou et al., Science 2018]. We demonstrate that both the Response and the original paper contain additional faults, for example, in the power determination and in the normalization of the rate to the catalyst volume, and exhibit misconceptions regarding the thermo-optic response of metal nanostructures. The burden of proof required by the proposal of a novel physical mechanism has simply not been met, especially when the existing data can be modeled exquisitely by conventional theory.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Referee Report

1 major / 1 minor

Summary. This manuscript is a follow-up Comment critiquing the Response by Zhou et al. to earlier criticism of their Science 2018 paper on distinguishing thermal versus non-thermal (hot-carrier) contributions in plasmonic photocatalysis. It argues that additional data supplied in the Response further validates the original criticism: temperature measurements were underestimated because of default thermal-camera settings and incorrect thermometer positioning, leading Zhou et al. to claim non-thermal effects. The manuscript identifies experimental-setup flaws, factual errors in the Response, problems with power determination and rate normalization to catalyst volume, and misconceptions about the thermo-optic response of metal nanostructures. It concludes that the burden of proof for a novel non-thermal mechanism has not been met because the existing data can be modeled by conventional thermal theory.

Significance. If the identified measurement inaccuracies are confirmed and corrected temperatures are shown to account for the observed rate enhancements via standard Arrhenius kinetics, the result would be significant for the plasmonic-photocatalysis community. It would reinforce that apparent enhancements previously attributed to hot carriers are thermal in origin, prompting systematic re-examination of similar claims that rely on optical thermometry. The manuscript correctly flags plausible setup issues (thermometer placement, camera defaults) that are known sources of systematic error in catalyst-temperature reporting.

major comments (1)
  1. [Abstract and discussion of Response data] The central claim that 'the existing data can be modeled exquisitely by conventional theory' (abstract) is load-bearing yet unsupported by any explicit quantitative step: no Arrhenius re-fit, error propagation, or rate-versus-corrected-temperature plot is presented that demonstrates the measurement errors (default thermal-camera settings and thermometer mis-positioning) are large enough to eliminate the need for non-thermal contributions. Without this calculation the assertion remains an inference rather than a demonstrated result.
minor comments (1)
  1. The manuscript states that both the Response and the original paper contain 'additional faults' in power determination and rate normalization, but does not supply the specific numerical discrepancies or corrected values; adding these concrete examples would improve clarity.

Simulated Author's Rebuttal

1 responses · 0 unresolved

We thank the referee for their constructive feedback on our manuscript. Below we address the major comment point by point.

read point-by-point responses

  1. Referee: [Abstract and discussion of Response data] The central claim that 'the existing data can be modeled exquisitely by conventional theory' (abstract) is load-bearing yet unsupported by any explicit quantitative step: no Arrhenius re-fit, error propagation, or rate-versus-corrected-temperature plot is presented that demonstrates the measurement errors (default thermal-camera settings and thermometer mis-positioning) are large enough to eliminate the need for non-thermal contributions. Without this calculation the assertion remains an inference rather than a demonstrated result.

    Authors: The quantitative demonstration that the data are consistent with conventional Arrhenius kinetics once temperatures are corrected appears in our supporting theoretical study (Dubi and Sivan, arXiv:1805.03831), which is cited in the manuscript. The present work focuses on the additional experimental evidence supplied in Zhou et al.'s Response and shows that it further validates the identified measurement errors. We will revise the manuscript to include an explicit cross-reference to the specific modeling results in that prior work, thereby making the connection to the central claim more direct. revision: partial

Circularity Check

0 steps flagged

No load-bearing circularity; critique grounded in experimental analysis with incidental self-reference

full rationale

This manuscript is a technical comment that identifies specific experimental flaws (default thermal-camera settings, thermometer positioning, power determination, rate normalization) in the Response and original Zhou et al. work. While it references the authors' own prior Comment and arXiv preprints to frame the debate, these citations establish context rather than serving as the sole or load-bearing justification for the claims. No equations, fitted parameters, predictions, or first-principles derivations are presented that reduce to self-referential inputs by construction. The assertion that existing data can be modeled by conventional theory is stated without new quantitative re-fitting in the provided text, but this is an unsupported assertion rather than a circular reduction. The derivation chain relies on direct examination of external data and standard experimental practice, qualifying as self-contained.

Axiom & Free-Parameter Ledger

0 free parameters · 0 axioms · 0 invented entities

No new derivations, free parameters, or invented entities are introduced; the paper critiques experimental methodology in prior work.

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discussion (0)

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Reference graph

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