NOVELTY - A copper-silver nano-alloy negative electrode comprises sodium borohydride/hydrogen peroxide fuel battery with copper foil as substrate on which silver and copper deposited, with primary dendritic crystal of 10-30 mu m long, secondary dendritic crystal of 500 nm-1 mu m in spacing, 4-20 mu m long, cubic dendritic crystal of 10-30 nm in spacing and 2-20 nm long.    USE - Copper-silver nano-alloy negative electrode used for fuel battery (claimed).    ADVANTAGE - The negative electrode has low cost and enhanced catalysis effect.    DETAILED DESCRIPTION - A copper-silver nano-alloy negative electrode comprises sodium borohydride/hydrogen peroxide fuel battery with copper foil as substrate on which silver and copper deposited in ratio of x:1-x. The product is represented as tree branch; the primary dendritic crystal of 10-30 mu m long; the secondary dendritic crystal of 500 nm-1 mu m in spacing and 4-20 mu m long; and the cubic dendritic crystal is 10-30 nm in spacing and 2-20 nm long.    x=0.3-0.7.    An INDEPENDENT CLAIM is included for a preparation of copper-silver nano-alloy negative electrode comprising:    (A) milling surface of the copper foil substrate by gold-phase sand paper, ultrasonically cleaning the milled copper foil substrate in the de-ionized water for 10 minutes ultrasonically cleaning for 10 minutes in acetone solution, with ultrasonic power of 100 W, adding polyethylene glycol (594.5 mg) with 10000 in molecular weight, nitrate radical (85.1 mg), copper nitrate (121.4 mg) and potassium nitrate (510.6 mg) sequentially added in deionized water and uniformly stirred, obtaining electrolyte to prepare copper-silver nano-alloy negative electrode, preparing saturated potassium chloride solution, adding deionized water (40 ml) in the flask, adding potassium chloride (37 g), and uniformly stirring to obtain saturated potassium chloride solution;    (B) dissolving potassium nitrate (90 g) in deionized water (100 g), heating deionized water added with potassium nitrate at 60 degrees C, maintaining heat, adding agar (9.5 g), increasing temperature to dissolve agar at 90 degrees C to obtain mixing solution comprising potassium nitrate and agar, injecting mixing solution into U-shaped pipe, and cooling mixing solution at 20 degrees C to obtain salt bridge of the mixture of the potassium nitrate and the agar;and    (C) using tri-electrode system, vertically placing platinum net and copper foil at two ends of container comprising electrolyte and dipping in electrolyte, corresponding milled surface of copper foil with platinum net, arranging two ends of salt bridge in electrolyte and saturated potassium chloride solution to connect electrolyte and saturated potassium chloride solution, connecting working electrode, auxiliary electrode and reference electrode with electrochemical working station by lead wire, depositing copper-silver nano-alloy branch crystal on copper foil substrate, depositing, maintaining constant potential E as - 0.6 V, depositing duration 600 seconds, at 20 degrees C, sampling spacing as 0.1 V/second and sensitivity as 0.01 A/V, and obtaining copper foil substrate covered with copper-silver nano-alloy thin film to obtain copper-silver nano-alloy negative electrode.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic diagram of the preparation of copper-silver nano-alloy negative electrode. (Drawing includes non-English language text)