# Single-atom catalysis full-text reading pack

## Evidence standard

This pack uses the five PDFs attached to **Single-Atom Catalysis - Full-Text Journal Club**. Page numbers refer to PDF pages. Performance measures from different reactions are kept separate and are not compared as if interchangeable.

## PDF verification

| Paper | DOI | Year | Pages |
|---|---|---:|---:|
| Lang et al., “Non defect-stabilized thermally stable single-atom catalyst” | 10.1038/s41467-018-08136-3 | 2019 | 10 |
| Sun et al., “Breaking the scaling relationship via thermally stable Pt/Cu single atom alloys for catalytic dehydrogenation” | 10.1038/s41467-018-06967-8 | 2018 | 9 |
| Ouyang et al., “Directing reaction pathways via in situ control of active site geometries in PdAu single-atom alloy catalysts” | 10.1038/s41467-021-21555-z | 2021 | 11 |
| He et al., “Building up libraries and production line for single atom catalysts with precursor-atomization strategy” | 10.1038/s41467-022-33442-2 | 2022 | 10 |
| Qi et al., “Highly selective and robust single-atom catalyst Ru₁/NC for reductive amination of aldehydes/ketones” | 10.1038/s41467-021-23429-w | 2021 | 11 |

## Paper map

### Lang et al. 2019

**Authors:** Rui Lang; Wei Xi; Jin-Cheng Liu; Yi-Tao Cui; Tianbo Li; Adam Fraser Lee; Fang Chen; Yang Chen; Lei Li; Lin Li; Jian Lin; Shu Miao; Xiaoyan Liu; Ai-Qin Wang; Xiaodong Wang; Jun Luo; Botao Qiao; Jun Li; Tao Zhang.

**Research question:** Can Fe₂O₃ stabilize high concentrations of isolated Pt without pre-existing defects, and can nanoparticle-to-atom conversion improve methane combustion?

**Catalyst/reaction:** Pt/Fe₂O₃; methane combustion.

**Supported finding:** At 700 °C, methane conversion rose from about 18% to 65% over four hours as Pt nanoparticles converted toward isolated Pt. **PDF p. 6, Fig. 6.**

**Conditions:** 0.5 vol% CH₄, 3 vol% O₂, He balance, 30 mL min⁻¹; 300–700 °C, then held at 700 °C.

**Limitation:** Clusters appeared at ≥2 wt% Pt; the estimated isolated-atom capacity was near 1.5 wt% for 10 m² g⁻¹ Fe₂O₃. **PDF p. 4.**

**Discussion questions:**

1. Is time-dependent activation plus post-reaction Pt₁ evidence sufficient without operando site-specific proof?
2. Is redispersion best treated as synthesis, activation, or both?

### Sun et al. 2018

**Authors:** Guodong Sun; Zhi-Jian Zhao; Rentao Mu; Shenjun Zha; Lulu Li; Sai Chen; Ketao Zang; Jun Luo; Zhenglong Li; Stephen C. Purdy; A. Jeremy Kropf; Jeffrey T. Miller; Liang Zeng; Jinlong Gong.

**Research question:** Can isolated metallic Pt in Cu improve propane-dehydrogenation selectivity and stability above 500 °C?

**Catalyst/reaction:** 0.1Pt10Cu/γ-Al₂O₃ single-atom alloy; propane dehydrogenation.

**Supported finding:** The paper reports about 90% propylene selectivity and 10.6 mol gPt⁻¹ h⁻¹ at 520 °C; the 120-hour test retained an isolated-Pt CO-DRIFTS signature. Figure 5 also reports a deactivation rate of 0.0005 h⁻¹ versus 0.07 h⁻¹ for Pt/Al₂O₃. **PDF p. 6, Fig. 5.**

**Conditions for the Figure 5 result:** The **Figure 5 caption on PDF p. 6** specifies atmospheric pressure, propane WHSV 4 h⁻¹, 250 mg catalyst, C₃H₈/H₂ = 1/1, balance N₂, and 50 mL min⁻¹ total flow. The article’s narrative summary on **PDF p. 2 instead states C₃H₈/N₂ = 1/1** while also giving atmospheric pressure, 520 °C, and WHSV 4 h⁻¹. These feed descriptions conflict; they are reported separately here and are not silently harmonized. For interpretation of the Figure 5 result, the caption-specific feed is retained.

**Limitation:** Cu sintering and rapid deactivation occurred at 600 °C. Regenerated-catalyst EXAFS was unavailable, so partial Pt sintering after oxidation–reduction cycling could not be excluded. **PDF pp. 6–7.** The contradictory feed descriptions on pp. 2 and 6 are an additional reporting limitation.

**Discussion questions:**

1. Which structural measurement most strongly ties selectivity to isolated Pt?
2. How should the page-2/page-6 feed conflict affect reproducibility and confidence in the reported performance?

### Ouyang et al. 2021

**Authors:** Mengyao Ouyang; Konstantinos G. Papanikolaou; Alexey Boubnov; Adam S. Hoffman; Georgios Giannakakis; Simon R. Bare; Michail Stamatakis; Maria Flytzani-Stephanopoulos; E. Charles H. Sykes.

**Research question:** Can CO coverage reversibly switch Pd ensemble size and redirect ethanol dehydrogenation?

**Catalyst/reaction:** Pd₀.₀₂Au₀.₉₈/SiO₂; ethanol dehydrogenation.

**Supported finding:** The single-atom-alloy phase gave <20% conversion and 100% acetaldehyde/H₂ selectivity to 300 °C. CO-induced Pd clusters raised conversion to as much as 90% but formed ethyl acetate, CO, and CH₄; a final 30 °C CO treatment restored single-atom-like selectivity. **PDF p. 7, Fig. 4.**

**Conditions:** 300 mg catalyst; 2 wt% ethanol/He; 12 mL min⁻¹; GHSV 2400 mL h⁻¹ gcat⁻¹; 2 h per temperature; CO treatments at 30 and 70 °C.

**Limitation:** Clusters re-dispersed at high reaction temperature; repeated switching caused carbon buildup and loss of complete reversibility. The model shifted DFT CO-binding energy by +0.2 eV. **PDF pp. 5 and 7.**

**Discussion questions:**

1. Why is a within-sample atom↔cluster switch stronger than separate catalyst comparisons?
2. How should mechanism be assigned when the reaction changes ensemble size?

### He et al. 2022

**Authors:** Xiaohui He; Hao Zhang; Xingcong Zhang; Ying Zhang; Qian He; Hongyu Chen; Yujie Cheng; Mi Peng; Xuetao Qin; Hongbing Ji; Ding Ma.

**Research question:** Can precursor atomization produce diverse SACs continuously above kilogram-per-day scale with uniform structure and function?

**Catalyst/reaction:** Pd₁/FeOₓ scale demonstration and a 19-SAC library; Suzuki–Miyaura coupling.

**Supported finding:** A line with 34 atomizers, 16 infrared lamps, and two 2-m belts exceeded 1 kg day⁻¹. The production-line description and four ~10 g sampled batches are on **PDF p. 3**; structural uniformity is shown on **PDF p. 6, Fig. 4**; catalytic reproducibility is discussed on **PDF p. 5**; Figure 5d–f is on **PDF p. 7**.

**Conditions:** ~120 g m⁻² FeOₓ; belt ~1 cm min⁻¹; 2.45 mmol L⁻¹ precursor at ~40 mL h⁻¹; calcination at 400 °C for 2 h. Coupling: 5 mg catalyst, 0.5 mmol bromobenzene, 0.75 mmol phenylboronic acid, 1.5 mmol K₂CO₃, EtOH/H₂O, 40 °C.

**Limitation:** Throughput was demonstrated for Pd₁/FeOₓ; detailed uniformity used four ~10 g samples and one reaction family. Calcination remained separate, and TOF assumed 100% Pd dispersion.

**Discussion questions:**

1. What sampling plan would validate a uniform 1 kg day⁻¹ product?
2. Which operation is most likely to limit further scale-up?

### Qi et al. 2021

**Authors:** Haifeng Qi; Ji Yang; Fei Liu; LeiLei Zhang; Jingyi Yang; Xiaoyan Liu; Lin Li; Yang Su; Yuefeng Liu; Rui Hao; Aiqin Wang; Tao Zhang.

**Research question:** Can Ru–N coordination tune hydrogen activation for selective and robust primary-amine synthesis?

**Catalyst/reaction:** Ru₁/NC with RuN₅, RuN₄, or RuN₃ environments; reductive amination.

**Supported finding:** Ru₁/NC-900–800NH₃ gave 97% furfurylamine yield and 170.7 gFAM gRu⁻¹ h⁻¹, versus 53% for RuNP-1000. **PDF pp. 5–6, Table 2.** Robustness comparisons are on **PDF pp. 6–7, Fig. 5.**

**Conditions:** 2 mmol furfural; Ru:furfural 1:400; 3 g methanol; 0.5 MPa NH₃; 2 MPa H₂; 100 °C; 10 h.

**Limitation:** EXAFS coordination numbers have estimated ±20% uncertainty; mechanism is indirect; the pressurized 10-hour batch test is not scale-up evidence.

**Discussion questions:**

1. Are coordination number and electronic structure isolated well enough for causal attribution?
2. Which practical evidence is strongest: yield, poison resistance, reuse, or substrate scope?

## How the papers connect

The five papers form an evidence chain, not a performance ranking. Lang, Qi, and He address synthesis and structural assignment; Lang, Sun, and Qi test thermal or chemical robustness; Ouyang provides the strongest within-sample causal atom↔cluster experiment; and He reports >1 kg day⁻¹ production while revealing validation gaps. Collectively, they show that isolated-site evidence is strongest when structure is tied to the same catalyst state under relevant conditions and compared with clustered or nanoparticle controls.

## 60-minute agenda

| Time | Minutes | Activity |
|---|---:|---|
| 0:00–0:05 | 5 | Frame the causal question and agree on evidence standards |
| 0:05–0:14 | 9 | Lang: oxidative redispersion, site capacity, and methane combustion |
| 0:14–0:23 | 9 | Sun: Pt/Cu isolation, propane-dehydrogenation selectivity, and 520 °C stability |
| 0:23–0:35 | 12 | Ouyang: atom↔cluster switching as a causal mechanism experiment |
| 0:35–0:44 | 9 | Qi: Ru–N coordination, selective reductive amination, and robustness |
| 0:44–0:54 | 10 | He: production-line evidence, batch uniformity, and scale-up boundaries |
| 0:54–1:00 | 6 | Cross-paper synthesis and decisive missing experiments |
| **Total** | **60** | |

## Missing or conflicting evidence

All PDFs were readable. Sun 2018 contains conflicting feed descriptions: p. 2 states C₃H₈/N₂ = 1/1, while the p. 6 Figure 5 caption states C₃H₈/H₂ = 1/1 with balance N₂ and gives 50 mL min⁻¹ total flow and 250 mg catalyst. The conflict is unresolved in the main PDF.