Green synthesis of Size‐Controlled copper oxide nanoparticles as catalysts for H ₂ production from industrial waste aluminum

Abstract

Extensive research and development in the processes of production and generation of hydrogen are needed to make renewable hydrogen cost-competitive with fossil hydrogen. As a result, developing hydrogen energy from low-cost components and synthesizing it from renewable resources is an important issue that can be considered a global challenge. The current research provided a continuous H 2 energy production from waste aluminum in a water medium using copper oxide nanoparticles (CuO NPs) as catalysts in the reaction. CuO NPs have been prepared by a green, easy, inexpensive, and systematic method using Catha edulis L. (Khat) extract as reducing and capping agents. Separately, CuO NPs prepared in an alkaline media using the conventional hydrothermal process have been described and reported for comparison.

Productive and Sustainable H2 Production from Waste Aluminum Using Copper Oxides-Based Graphene Nanocatalysts: A Techno-Economic Analysis

“…These peaks confirm the reduction capability of the plant extract to reduce the copper precursor to a pure phase of CuO [75]. The presence of a broad peak at wavenumber 780 cm −1 is an indication of the fine nanoparticles of CuO prepared by the extract [46,76]. Furthermore, Figure 8a shows two broad and intense peaks at 1350 and 1550 cm −1 as an indication of the presence of graphene in the samples [73,76].…”

“…Most importantly, all the proposed Al-H 2 O reactions, either in neutral or basic conditions and with nanocatalysts, could result in an identical number of H 2 moles, whatever the reaction conditions are [46,50]. In other words, for every 2 moles of aluminum, there will be 3 moles of hydrogen gas that are released during the reaction.…”

“…CuO NPs were synthesized using a green method that uses the extract of Catha edulis L. as a promoter, reducer, and capping agent. The procedure for preparing the extract solution of Catha edulis L. was detailed in our previous works [46,47]. Briefly, a few grams of the dry leaves were extracted in a water solvent at ~100 • C until it was transformed into a reddish homogenous color.…”

“…This explains why particles on graphene sheets show good dispersion and have a larger surface area. To this end, CuO and Cu 2 O NP-decorated graphene nanosheets possess extraordinary properties that enable them to meet the needs of rapid technological developments and attain high-stability particles [36][37][38][39][40][41][42][43][44][45][46][47][48][49][50][51][52][53]. The aforementioned properties make copper-graphene composites ideal candidates for heterogeneous catalytic applications [26].…”

Silver-Assisted Hydrogen Evolution from Aluminum Oxidation in Saline Media

“…Other feasible methods are mainly focused on the modification of aluminum composition and structure. That can be done via its melting together with various metals (e.g., Fe, Sn, Cu, Li, Ga, In, Sn) [ 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 ] or ball milling with salts (e.g., NaCl, KCl, NiCl 2 , CoCl 2 ) [ 52 , 53 , 54 , 55 , 56 ], oxides and hydroxides (Bi(OH) 3 , AlOOH, Al(OH) 3 , Al 2 O 3 , TiO 2 , Co 3 O 4 , Cr 2 O 3 , MoO 3 , Bi 2 O 3 , CuO, Cu 2 O) [ 57 , 58 , 59 , 60 , 61 , 62 , 63 ], and metals (Cu, Bi, Sn, Pb, Fe, Ni, Zn, Ga, In) [ 56 , 64 , 65 , 66 , 67 , 68 , 69 , 70 , 71 ]. Experiments with aluminum granules and distilled water under 200–280 °C proved that aluminum vulnerability to oxidation was critically dependent on the amount of impurities in aluminum alloys and their nature [ 72 ].…”