Unprotected and interconnected Ru0 nano-chain networks: advantages of unprotected surfaces in catalysis and electrocatalysis

Surfactant- and support-free metallic, interconnected and unprotected Ru nano-chain networks are synthesized and screened for catalytic nitro arene hydrogenation and OER studies. Their excellent catalytic and electrocatalytic activities are due to the advantages of having unprotected Ru0 surfaces.


Preparation of Calibration Curves for Finding the Real Concentration at Each Point of the Hydrogenation Reaction.
To study the kinetics and other necessary parameters like conversion, selectivity, yield, TON, and TOF, the actual concentrations of the reactant at each point of the reaction should be known. To find the real concentration of any substrate with a detectable and sensitive UV-Vis absorption peak with respect to the change in concentration, preparation of calibration curve of the substrate is an easy way. Calibration curves are the linear plot of the absorbance vs.
concentration of the same substrate under study but with different known concentrations. As the absorbance is a concentration dependent phenomenon, any change in concentration will bring out a linear change in the absorbance too. If the concentration of the substrate solution is increased gradually, the corresponding absorbance will also increase. As a consequence of this linear variation, the plot of absorbance values against their respective concentration will also give a linear plot with a positive slope. According to the Lambert-Beer law, the absorbance and concentration of a compound in terms of calibration curves can be related as given equation 1.
The details of concentrations of each nitro compound is tabulated as Table S1. The respective UV-Vis spectra and the calibration curves are also provided in Figures S1, A-F. Using these calibration curves, the absorbance values measured from the time-dependent UV-Vis spectra of each hydrogenation reaction for both catalysts were converted into their corresponding real concentrations accordingly for further kinetic studies.

Preparation of Samples for Further Spectroscopic and Microscopic Characterizations.
The synthesized interconnected Ru 0 nano-chain networks Ru-30 and Ru-60 were characterized using UV-Vis, HR-TEM, EDS, XRD and XPS studies. The colloidal solutions of

X-Ray Diffraction (XRD) Studies.
X-ray diffraction (XRD) patterns of Ru-30, Ru-45 and Ru-60 were obtained at a scan rate of 5° per min within the range of 10° to 90°. The resultant XRD patterns are given as Figure S2.
All the three catalysts gave almost similar XRD patterns with the variation in their net intensities.  Other than time and rate constant of any catalytic reactions, quantitative parameters like conversion (X), selectivity (S) and yield will give better insight into the catalytic activity of the catalyst used. Conversion can be defined as the total quantity of the reacted reactant or the product(s) formed whereas selectivity of a product is defined as the fraction of the desired product formed in the reaction with other possible products. Similarly, Yield can be defined as the ratio of the product of the conversion and the selectivity of the desired product to hundred.
Here, as an example we have calculated the X, S and Y for the hydrogenation of 2-Bromo Similarly, Selectivity is given as Where, nP(t) = is the number of products formed after time 't' nP(t 0 ) = is the number of products in beginning (i.e., t= 0) nR(t0) = is the number of reactants in beginning (i.e., t= 0) As it was a homogenous reaction and the catalyst and the product had the same volume, we can relate the number of reactant/product molecules directly to their concentration.

S = 100%
Note, there was no other byproduct formed. By adapting the same procedure the conversion, selectivity and yield of all other reactions for both catalysts were done and the final results are given in Table 1 provided in the main text.

Determination of turnover number (TON) and turnover frequency for the catalytic hydrogenations of nitroarenes by both Ru-30, Ru-45 and Ru-60.
Turnover number (TON) and turnover frequency (TOF) are the other two important quantitative parameters for any catalytic study. As seven different nitroarenes were subjected to this catalytic hydrogenation by our unprotected and interconnected Ru 0 nano-chain networks, both TON and TOF have become the essential quantities when comparing their catalytic activity between them and among all other existing catalyst for the same and similar type of nitroarenes hydrogenation. TON can be simply defined as the ratio of the number of reactants reacted to number particles catalyzed. Hence, it just a number and gives a semi-quantitative information.
On the other hand, TOF is a quantitative measure which gives the details on the number of reactants reacted per number of particles in unit time. Since the catalytic study was homogeneous and the volume of both reactants/products and the catalyst are having the same volume, we can take the number of reactants to be equal to the concentration of the same. It is applicable for the catalyst too.
TON =n(product) / n(catalyst) We know that, Since both product and catalyst are in the same reaction vessel the volume for both is the same: V, the volume can be canceled down: Following this expression, TON of all the catalytic reactions were calculated and listed in the

Determination of TOF value for the electrocatalytic water splitting.
Turnover frequency for an electrocatalytic water splitting reactions can be done in more than one way, in our case we have opted the method of using OER current at particular over voltage and the surface concentration of Ru atoms at the modified GC working electrode which was calculated from the amount catalyst we added to modify the GC electrode. The corresponding expression is,

TOF= i×N A / A × F × n × ᴦ
Where

Determination of Specific Activity:
Specific activity of Ru-60 modified GC was calculated using following equation

E (V vs RHE)
Post cycle CV Table S1 S