## 2 Experimental Section  
### Sample Preparation and Characterizing  
Figure 1 shows the experimental setup for the preparation of electrodeposition patterned copper foam. A copper sheet was used as the anode, and a copper foam was used as the cathode. The copper foam ((porous per inch) PPI: 95, purity: 99%) was provided by the Kunshan Guangjiayuan Co. Ltd. (Kunshan, China). The copper foam had a thickness of 1.0 mm, and it was cut into 40 mm (L) \(\times\) 20 mm (W) pieces. The electrolytes were composed of 0.2 M CuSO\({}_{4}\), 1.5 M H\({}_{2}\)SO\({}_{4}\), and 0.5 M Na\({}_{2}\)SO\({}_{4}\). CuSO\({}_{4}\).5H\({}_{2}\)O, H\({}_{2}\)SO\({}_{4}\), and Na\({}_{2}\)SO\({}_{4}\) were all of analytical grade, and they were obtained from the  
Sinopharm Chemical Reagent Co. Ltd. (Shanghai, China). The distance between the anode and cathode was 2 cm. Both the anode and cathode were connected to a programmable DC power supply (M8852, Maynuo Electronic Co., Ltd., Nanjing, China). During the experiment, the current and voltage data were collected by a computer.  
When DC power is applied to the system, the following chemical reaction occurs at the anode:  
\[\text{Cu}-2\text{e}^{-}=\text{Cu}^{2+} \tag{1}\]  
At the same time, the following chemical reaction occurs at the cathode:  
\[\text{Cu}^{2+}+2\text{e}^{-}=\text{Cu}\downarrow \tag{2}\]  
Thus, copper ion is deposited on the cathode.  
If the power is sufficiently high, another chemical reaction happens at the cathode:  
\[2\text{H}^{+}+2\text{e}^{-}=\text{H}_{2}\uparrow \tag{3}\]  
The hydrogen ion in the electrolyte becomes hydrogen, which generates bubbles in the system. Hydrogen bubbles can help deposited copper to form a porous structure.  
[PERSON] et al. [18] have reported that, using the linearly increasing current density method, deposited copper can form a tree-like porous copper, which has abundant dendritic structures. In this study, we used the same method. The initial current density was set to 0.1 A/cm\({}^{2}\), and the current density growth rate was set to 0.167 mA/cm\({}^{2}\)-s. The deposition times for different samples varied from 195 to 300 s, as shown in Table 1. CF#195s, CF#255s, and CF#300s refer to the samples with the deposition times of 195 s, 255 s, and 300 s, respectively. CF#0s refers to the sample with the deposition time of 0 s, which is the original copper foam without any deposition, and it was as a contrast. After deposition, the samples were washed with distilled water and treated at high temperature for 2 h in a reducing atmosphere.  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**No.** & **Sample** & **Deposition Time(s)** \\ \hline
1 & CF\#0s & 0 \\ \hline
2 & CF\#195s & 195 \\ \hline
3 & CF\#255s & 255 \\ \hline
4 & CF\#300s & 300 \\ \hline \hline \end{tabular}
\end{table}
Table 1: Deposition times for different samples.  
Figure 1: Experimental setup for the preparation of electrodeposition-patterned copper foam.  
The surface morphology of prepared samples was studied by metallographic microscopy (10 XB-PC, Shanghai Optical Instrument Co. Ltd., Shanghai, China) and scanning electron microscopy (SEM, EVO MA10, Carl Zeiss AG, Jena, Germany).  
The wettability of different samples was measured by depositing a 4-\(\upmu\)L water droplet using a needle. A high-speed camera (Pantom V211, Vision research Co. Ltd., Wayne, NJ, USA) was used to record this phenomenon.